Device and method for transmitting uplink control channel in wireless communication system

ABSTRACT

The present specification relates to a device and method for transmitting an uplink control channel in a wireless communication system. Disclosed in the present specification is a method for transmitting a physical uplink control channel by means of a UE, the method including: a step for generating a first HARQ-ACK codebook related to a first PUCCH; a step for generating a second HARQ-ACK codebook related to a second PUCCH; and a step for transmitting simultaneously the first PUCCH and the second PUCCH or one PUCCH among the first PUCCH and the second PUCCH to a base station in one slot on the basis of a plurality of indicators. According to the present embodiments, the sequence for transmitting a plurality of PUCCHs including respectively different HARQ-ACKs in one slot is clarified, and thus the targeted performance of a 5G wireless communication system intended to simultaneously provide various types of traffic (eURLLC, eMBB) can be achieved.

TECHNICAL FIELD

The present disclosure relates to wireless communication and, moreparticularly, to a device and method for transmitting an uplink controlchannel in a wireless communication system, a device and method forreceiving an uplink control channel in a wireless communication system,and a device and method for controlling a downlink for the same.

BACKGROUND ART

After commercialization of 4th generation (4G) communication system, inorder to meet the increasing demand for wireless data traffic, effortsare being made to develop new 5th generation (5G) communication systems.The 5G communication system is called as a beyond 4G networkcommunication system, a post LTE system, or a new radio (NR) system. Inorder to achieve a high data transfer rate, 5G communication systemsinclude systems operated using the millimeter wave (mmWave) band of 6GHz or more, and include a communication system operated using afrequency band of 6 GHz or less in terms of ensuring coverage so thatimplementations in base stations and terminals are under consideration.

A 3rd generation partnership project (3GPP) NR system enhances spectralefficiency of a network and enables a communication provider to providemore data and voice services over a given bandwidth. Accordingly, the3GPP NR system is designed to meet the demands for high-speed data andmedia transmission in addition to supports for large volumes of voice.The advantages of the NR system are to have a higher throughput and alower latency in an identical platform, support for frequency divisionduplex (FDD) and time division duplex (TDD), and a low operation costwith an enhanced end-user environment and a simple architecture.

In order to alleviate the path loss of radio waves and increase thetransmission distance of radio waves in the mmWave band, in 5Gcommunication systems, beamforming, massive multiple input/output(massive MIMO), full dimensional MIMO (FD-MIMO), array antenna, analogbeam-forming, hybrid beamforming that combines analog beamforming anddigital beamforming, and large scale antenna technologies are discussed.In addition, for network improvement of the system, in the 5Gcommunication system, technology developments related to evolved smallcells, advanced small cells, cloud radio access network (cloud RAN),ultra-dense network, device to device communication (D2D), vehicle toeverything communication (V2X), wireless backhaul, non-terrestrialnetwork communication (NTN), moving network, cooperative communication,coordinated multi-points (CoMP), interference cancellation, and the likeare being made. In addition, in the 5G system, hybrid FSK and QAMmodulation (FQAM) and sliding window superposition coding (SWSC), whichare advanced coding modulation (ACM) schemes, and filter bankmulti-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparsecode multiple access (SCMA), which are advanced connectivitytechnologies, are being developed.

Meanwhile, in a human-centric connection network where humans generateand consume information, the Internet has evolved into the Internet ofThings (IoT) network, which exchanges information among distributedcomponents such as objects. Internet of Everything (IoE) technology,which combines IoT technology with big data processing technologythrough connection with cloud servers, is also emerging. In order toimplement IoT, technology elements such as sensing technology,wired/wireless communication and network infrastructure, serviceinterface technology, and security technology are required, so that inrecent years, technologies such as sensor network, machine to machine(M2M), and machine type communication (MTC) have been studied forconnection between objects. In the IoT environment, an intelligentinternet technology (IT) service that collects and analyzes datagenerated from connected objects to create new value in human life canbe provided. Through the fusion and mixture of existing informationtechnology (IT) and various industries, IoT can be applied to fieldssuch as smart home, smart building, smart city, smart car or connectedcar, smart grid, healthcare, smart home appliance, and advanced medicalservice.

Accordingly, various attempts have been made to apply the 5Gcommunication system to the IoT network. For example, technologies suchas a sensor network, a machine to machine (M2M), and a machine typecommunication (MTC) are implemented by techniques such as beamforming,MIMO, and array antennas. The application of the cloud RAN as the bigdata processing technology described above is an example of the fusionof 5G technology and IoT technology. Generally, a mobile communicationsystem has been developed to provide voice service while ensuring theuser's activity.

A future 5G technology requires lower latency data transmission due tothe advent of a new application, such as real-time control and tactileInternet, and the 5G data request latency is expected to be lowered downto 1 ms. 5G aims to provide approximately 10 times lower data latencythan before. In order to solve this problem, it is expected that acommunication system using a mini-slot having a shorter TTI period(e.g., 0.2 ms), in addition to the existing slot (or subframe), will beproposed for 5G.

In relation to an enhanced ultra-reliable low latency communication(URLLC) that is being developed in 3GPP release 16, various technologiesfor providing lower latency and higher reliability are being discussed.In order to provide a lower latency time, transmission of an uplinkcontrol channel including two or more pieces of HARQ-ACK in one slot issupported. A UE may secure a lower latency time by enabling HARQ-ACKtransmission as quickly as possible in response to successful receptionof a downlink shared channel. In particular, when multiple PUCCHs formultiple HARQ-ACK transmissions exist in one slot, a procedure fortransmitting a PUCCH and HARQ-ACK timing should be newly defined.

DISCLOSURE OF INVENTION Technical Problem

A technical task of the present disclosure is to provide a device andmethod for transmitting an uplink control channel in a wirelesscommunication system, a device and method for receiving an uplinkcontrol channel in a wireless communication system, and a device andmethod for controlling a downlink for the same.

Another technical task of the present disclosure is to provide a methodfor transferring downlink control information for multiple PUCCHtransmissions and a method for determining HARQ-ACK information includedin PUCCHs.

Another technical task of the present disclosure is to provide a deviceand method for solving, by indicating multiple PUCCHs via whichdifferent pieces of HARQ-ACK are transmitted, collision of the multiplePUCCHs.

Another technical task of the present disclosure is to provide a methodfor transmitting a PDSCH group indicator indicating multiple PUCCHs, viawhich different pieces of HARQ-ACK are transmitted, to a UE by a basestation.

Another technical task of the present disclosure is to provide a methodfor defining k1, which indicates HARQ-ACK timing, in a unit smaller thana slot.

Another technical task of the present disclosure is to provide a methodfor transmitting an HARQ-ACK multiplexing indicator, which indicateswhether HARQ-ACK is multiplexed, to a UE by a base station.

Solution to Problem

An aspect of the present disclosure provides a method for transmitting aphysical uplink control channel (PUCCH) to a base station by a UE in awireless communication system. The method includes: generating a firstHARQ-ACK codebook associated with a first PUCCH; generating a secondHARQ-ACK codebook associated with a second PUCCH; and transmittingsimultaneously the first PUCCH and the second PUCCH to the base stationin one slot, or transmitting one PUCCH among the first PUCCH and thesecond PUCCH to the base station.

Here, the first PUCCH and the second PUCCH may correspond to a firstindicator and a second indicator, which have different values,respectively, and the one PUCCH may be determined to be the first PUCCHor the second PUCCH on the basis of the first and second indicators.

In an aspect, if the first PUCCH corresponds to the first indicatorhaving a value of 0, the second PUCCH corresponds to the secondindicator having a value of 1, and if the first PUCCH corresponds to thefirst indicator having a value of 1, the second PUCCH corresponds to thesecond indicator having a value of 0.

In another aspect, the method may further include receiving the firstindicator corresponding to the first PUCCH and the second indicatorcorresponding to the second PUCCH from the base station via a physicaldownlink control channel or radio resource control (RRC) signaling.

In another aspect, the first HARQ-ACK codebook may be generated in asemi-static scheme, and the second HARQ-ACK codebook may be generated ina dynamic scheme.

In another aspect, the transmitting simultaneously of the first PUCCHand the second PUCCH to the base station in one slot may be performed ina case where transmission of the first PUCCH and transmission of thesecond PUCCH do not collide, and the transmitting of one PUCCH among thefirst PUCCH and the second PUCCH may be performed in a case wheretransmission of the first PUCCH and transmission of the second PUCCHcollide, wherein the case where transmission of the first PUCCH andtransmission of the second PUCCH collide includes a case where aresource for the first PUCCH and a resource for the second PUCCH atleast partially overlap.

In another aspect, the transmitting of one PUCCH among the first PUCCHand the second PUCCH may further include multiplexing the first HARQ-ACKcodebook and the second HARQ-ACK codebook, and mapping the multiplexedfirst and second HARQ-ACK codebooks to the one PUCCH.

In another aspect, the method may further include receiving at least onephysical downlink shared channel (PDSCH) associated with the first PUCCHor the second PUCCH in a slot preceding the one slot, wherein aninterval between reception timing of the PDSCH and transmission timingof the PUCCH including an HARQ-ACK codebook associated with the at leastone PDSCH is defined in units of the number (=b) of symbols less thanthe number (=a) of symbols constituting the one slot or the precedingslot.

In another aspect, b is half of a.

In another aspect, each of the one slot and the preceding slot mayinclude multiple sub-slots, and the HARQ-ACK codebook associated withthe at least one PDSCH may include the same number of pieces of HARQ-ACKas the maximum number of PDSCHs receivable in the preceding slot.

In another aspect, the method may further include receiving asemi-persistently scheduled PDSCH in a slot preceding the one slot,wherein: if HARQ-ACK associated with the semi-persistently scheduledPDSCH cannot be transmitted after k1 slots from the preceding slot,transmission timing of a PUCCH including the HARQ-ACK associated withthe semi-persistently scheduled PDSCH is postponed until the one slot;and the k1 is an interval between reception timing of thesemi-persistently scheduled PDSCH and transmission timing of the PUCCHincluding the HARQ-ACK associated with the PDSCH.

In another aspect, the method may further include receiving atransmission period of the semi-statically scheduled PDSCH from the basestation, wherein an interval between the one slot and a slot after k1slots from the preceding slot is determined to be a multiple of thetransmission period.

An aspect of the present disclosure provides a method for receiving aphysical uplink control channel (PUCCH) from a UE by a base station in awireless communication system. The method includes: transmitting a firstphysical downlink shared channel (PDSCH) and a second PDSCH to the UE ina first slot; and receiving simultaneously a first PUCCH including afirst HARQ-ACK codebook associated with the first PDSCH and a secondPUCCH including a second HARQ-ACK codebook associated with the secondPDSCH from the UE in a second slot, or receiving one PUCCH among thefirst PUCCH and the second PUCCH from the UE.

Here, the first PUCCH and the second PUCCH may correspond to a firstindicator and a second indicator, which have different values,respectively, and the one PUCCH may be determined to be the first PUCCHor the second PUCCH on the basis of the first indicator and the secondindicator.

In an aspect, if the first PUCCH corresponds to the first indicatorhaving a value of 0, the second PUCCH may correspond to the secondindicator having a value of 1, and if the first PUCCH corresponds to thefirst indicator having a value of 1, the second PUCCH may correspond tothe second indicator having a value of 0.

In another aspect, the method may further include transmitting the firstindicator corresponding to the first PUCCH and the second indicatorcorresponding to the second PUCCH to the UE via a physical downlinkcontrol channel (PDCCH) or radio resource control (RRC) signaling.

In another aspect, the first HARQ-ACK codebook may be generated in asemi-static scheme, and the second HARQ-ACK codebook may be generated ina dynamic scheme.

In another aspect, the receiving simultaneously of the first PUCCH andthe second PUCCH from the UE in the second slot may be performed in acase where transmission of the first PUCCH and transmission of thesecond PUCCH do not collide, and the receiving of one PUCCH among thefirst PUCCH and the second PUCCH may be performed in a case wheretransmission of the first PUCCH and transmission of the second PUCCHcollide, wherein the case where transmission of the first PUCCH andtransmission of the second PUCCH collide includes a case where aresource for the first PUCCH and a resource for the second PUCCH atleast partially overlap.

In another aspect, the receiving of one PUCCH among the first PUCCH andthe second PUCCH may further include demultiplexing the one PUCCH so asto acquire the first HARQ-ACK codebook and the second HARQ-ACK codebook.

In another aspect, an interval between transmission timing of the firstand second PDSCHs and reception timing of the first and second PUCCHsmay be defined in units of the number (=b) of symbols less than thenumber (=a) of symbols constituting the first slot or the second slot.

In another aspect, the first slot may include each of multiplesub-slots, and an HARQ-ACK codebook associated with the first PDSCH mayinclude the same number of pieces of HARQ-ACK as the maximum number ofPDSCHs receivable in the first slot.

In another aspect, the first PDSCH is a semi-persistently scheduledPDSCH, and a transmission period associated with the first PDSCH may beconfigured by the base station; an interval between the first slot andthe second slot may be kl; if the first PUCCH cannot be transmitted inthe second slot, transmission timing of the first PUCCH may be postponeduntil a third slot; and the k1 may be an interval between receptiontiming of the first PDSCH and transmission timing of the first PUCCH.

Advantageous Effects of Invention

According to the present embodiments, a procedure of transmittingmultiple PUCCHs, which include different pieces of HARQ-ACKrespectively, in one slot is clarified, and thus the targetedperformance of a 5G wireless communication system intended toconcurrently provide various types of traffic (eURLLC and eMBB) can beachieved.

The effects obtainable in the present disclosure are not limited to theabove-mentioned effects, and other effects not mentioned will be clearlyunderstood by those of ordinary skill in the art from the followingdescription.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example of a wireless frame structure used in awireless communication system.

FIG. 2 illustrates an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system.

FIG. 3 is a diagram for explaining a physical channel used in a 3GPPsystem and a typical signal transmission method using the physicalchannel.

FIG. 4 illustrates an SS/PBCH block for initial cell access in a 3GPP NRsystem.

FIGS. 5A and 5B illustrates a procedure for transmitting controlinformation and a control channel in a 3GPP NR system.

FIG. 6 illustrates a control resource set (CORESET) in which a physicaldownlink control channel (PUCCH) may be transmitted in a 3GPP NR system.

FIG. 7 illustrates a method for configuring a PDCCH search space in a3GPP NR system.

FIG. 8 is a conceptual diagram illustrating carrier aggregation.

FIG. 9 is a diagram for explaining single carrier communication andmultiple carrier communication.

FIG. 10 is a diagram showing an example in which a cross carrierscheduling technique is applied.

FIG. 11 is a block diagram showing the configurations of a UE and a basestation according to an embodiment of the present disclosure.

FIG. 12 is a flowchart illustrating a method of transmitting multiplePUCCHs in one slot on the basis of an indicator according to anembodiment;

FIG. 13 is a diagram for describing an example of a method oftransmitting multiple PUCCHs in one slot;

FIG. 14 is a diagram for describing another example of a method oftransmitting multiple PUCCHs in one slot;

FIG. 15 is a diagram for describing a method of defining a unit of a k1value to be a sub-slot that is a smaller unit than a basic slot;

FIG. 16 is a diagram illustrating a situation in which multiple PUCCHtransmissions collide within one slot according to an example;

FIG. 17 is a diagram exemplarily illustrating multiple PDSCH candidatestransmittable over sub-slots according to an example;

FIG. 18 is a diagram describing an example of generating a semi-staticHARQ-ACK codebook based on a half slot;

FIG. 19 illustrates generation of a semi-static HARQ-ACK codebook basedon a half slot according to another example;

FIG. 20 illustrates a result of generating the semi-static HARQ-ACKcodebook according to FIG. 19;

FIG. 21 illustrates PUCCH transmission by a UE according to an HARQ-ACKmultiplexing indicator according to an example;

FIG. 22 illustrates PUCCH transmission of the UE according to anHARQ-ACK multiplexing indicator according to another example;

FIG. 23 is a diagram describing a method of determining a PUCCH resourcewhen k1 and PRI fields are not included (or indicated) in the UEaccording to an example; and

FIG. 24 is a diagram describing a method of transmitting, by the UE,HARQ-ACK bits associated with multiple SPS PDSCHs in one slot accordingto an example.

BEST MODE FOR CARRYING OUT THE INVENTION

Terms used in the specification adopt general terms which are currentlywidely used as possible by considering functions in the presentdisclosure, but the terms may be changed depending on an intention ofthose skilled in the art, customs, and emergence of new technology.Further, in a specific case, there is a term arbitrarily selected by anapplicant and in this case, a meaning thereof will be described in acorresponding description part of the disclosure. Accordingly, itintends to be revealed that a term used in the specification should beanalyzed based on not just a name of the term but a substantial meaningof the term and contents throughout the specification.

Throughout this specification and the claims that follow, when it isdescribed that an element is “connected” to another element, the elementmay be “directly connected” to the other element or “electricallyconnected” to the other element through a third element. Further, unlessexplicitly described to the contrary, the word “comprise” will beunderstood to imply the inclusion of stated elements but not theexclusion of any other elements unless otherwise stated. Moreover,limitations such as “more than or equal to” or “less than or equal to”based on a specific threshold may be appropriately substituted with“more than” or “less than”, respectively, in some exemplary embodiments.

The following technology may be used in various wireless access systems,such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier-FDMA(SC-FDMA), and the like. The CDMA may be implemented by a wirelesstechnology such as universal terrestrial radio access (UTRA) orCDMA2000. The TDMA may be implemented by a wireless technology such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). The OFDMAmay be implemented by a wireless technology such as IEEE 802.11(Wi-Fi),IEEE 802.16(WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like.The UTRA is a part of a universal mobile telecommunication system(UMTS). 3rd generation partnership project (3GPP) long term evolution(LTE) is a part of an evolved UMTS (E-UMTS) using evolved-UMTSterrestrial radio access (E-UTRA) and LTE-advanced (A) is an evolvedversion of the 3GPP LTE. 3GPP new radio (NR) is a system designedseparately from LTE/LTE-A, and is a system for supporting enhancedmobile broadband (eMBB), ultra-reliable and low latency communication(URLLC), and massive machine type communication (mMTC) services, whichare requirements of IMT-2020. For the clear description, 3GPP NR ismainly described, but the technical idea of the present disclosure isnot limited thereto.

Unless otherwise specified herein, the base station may include a nextgeneration node B (gNB) defined in 3GPP NR. Furthermore, unlessotherwise specified, a terminal may include a user equipment (UE).Hereinafter, in order to help the understanding of the description, eachcontent is described separately by the embodiments, but each embodimentmay be used in combination with each other. In the presentspecification, the configuration of the UE may indicate a configurationby the base station. In more detail, the base station may configure avalue of a parameter used in an operation of the UE or a wirelesscommunication system by transmitting a channel or a signal to the UE.

FIG. 1 illustrates an example of a wireless frame structure used in awireless communication system.

Referring to FIG. 1, the wireless frame (or radio frame) used in the3GPP NR system may have a length of 10 ms (Δf_(max)N_(f)/100)*T_(c)). Inaddition, the wireless frame includes 10 subframes (SFs) having equalsizes. Herein, Δf_(max)480*10³ Hz, N_(f)=4096,T_(c)=1/(Δf_(ref)*N_(f,ref)), Δf_(ref)=15*10³ Hz, and N_(f,ref)=2048.Numbers from 0 to 9 may be respectively allocated to 10 subframes withinone wireless frame. Each subframe has a length of 1 ms and may includeone or more slots according to a subcarrier spacing. More specifically,in the 3GPP NR system, the subcarrier spacing that may be used is 15*2PkHz, and p can have a value of p=0, 1, 2, 3, 4 as subcarrier spacingconfiguration. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz and 240 kHz maybe used for subcarrier spacing. One subframe having a length of 1 ms mayinclude 2^(μ) slots. In this case, the length of each slot is 2^(−μ0)ms. Numbers from 0 to 2^(μ)−1 may be respectively allocated to 2^(μ)slots within one wireless frame. In addition, numbers from 0 to10*2^(μ)−1 may be respectively allocated to slots within one subframe.The time resource may be distinguished by at least one of a wirelessframe number (also referred to as a wireless frame index), a subframenumber (also referred to as a subframe index), and a slot number (or aslot index).

FIG. 2 illustrates an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system. In particular, FIG. 2shows the structure of the resource grid of the 3GPP NR system.

There is one resource grid per antenna port. Referring to FIG. 2, a slotincludes a plurality of orthogonal frequency division multiplexing(OFDM) symbols in a time domain and includes a plurality of resourceblocks (RBs) in a frequency domain. An OFDM symbol also means one symbolsection. Unless otherwise specified, OFDM symbols may be referred tosimply as symbols. One RB includes 12 consecutive subcarriers in thefrequency domain. Referring to FIG. 2, a signal transmitted from eachslot may be represented by a resource grid including N^(size, μ)_(grid, x)*N^(RB) _(sc) subcarriers, and N^(slot) _(symb) OFDM symbols.Here, x=DL when the signal is a DL signal, and x =UL when the signal isan UL signal. N^(size, μ) _(grid, x) represents the number of resourceblocks (RBs) according to the subcarrier spacing constituent p (x is DLor UL) , and N^(slot) _(symb) represents the number of OFDM symbols in aslot. N^(RB) _(sc) is the number of subcarriers constituting one RB andN^(RB) _(sc)=12. An OFDM symbol may be referred to as a cyclic shiftOFDM (CP-OFDM) symbol or a discrete Fourier transform spread OFDM(DFT-s-OFDM) symbol according to a multiple access scheme.

The number of OFDM symbols included in one slot may vary according tothe length of a cyclic prefix (CP). For example, in the case of a normalCP, one slot includes 14 OFDM symbols, but in the case of an extendedCP, one slot may include 12 OFDM symbols. In a specific embodiment, theextended CP can only be used at 60 kHz subcarrier spacing. In FIG. 2,for convenience of description, one slot is configured with 14 OFDMsymbols by way of example, but embodiments of the present disclosure maybe applied in a similar manner to a slot having a different number ofOFDM symbols. Referring to FIG. 2, each OFDM symbol includes N^(size, μ)_(grid, x)*N^(RB) _(sc) subcarriers in the frequency domain. The type ofsubcarrier may be divided into a data subcarrier for data transmission,a reference signal subcarrier for transmission of a reference signal,and a guard band. The carrier frequency is also referred to as thecenter frequency (fc).

One RB may be defined by N^(RB) _(sc) (e. g., 12) consecutivesubcarriers in the frequency domain. For reference, a resourceconfigured with one OFDM symbol and one subcarrier may be referred to asa resource element (RE) or a tone. Therefore, one RB can be configuredwith N^(slot) _(symb)*N^(RB) _(sc) resource elements. Each resourceelement in the resource grid can be uniquely defined by a pair ofindexes (k, 1) in one slot. k may be an index assigned from 0 toN^(size, μ) _(grid, x)*N^(RB) _(sc)−1 in the frequency domain, and 1 maybe an index assigned from 0 to N^(slot) _(symb)−1 in the time domain.

In order for the UE to receive a signal from the base station or totransmit a signal to the base station, the time/frequency of the UE maybe synchronized with the time/frequency of the base station. This isbecause when the base station and the UE are synchronized, the UE candetermine the time and frequency parameters necessary for demodulatingthe DL signal and transmitting the UL signal at the correct time.

Each symbol of a radio frame used in a time division duplex (TDD) or anunpaired spectrum may be configured with at least one of a DL symbol, anUL symbol, and a flexible symbol. A radio frame used as a DL carrier ina frequency division duplex (FDD) or a paired spectrum may be configuredwith a DL symbol or a flexible symbol, and a radio frame used as a ULcarrier may be configured with a UL symbol or a flexible symbol. In theDL symbol, DL transmission is possible, but UL transmission isimpossible. In the UL symbol, UL transmission is possible, but DLtransmission is impossible. The flexible symbol may be determined to beused as a DL or an UL according to a signal.

Information on the type of each symbol, i.e., information representingany one of DL symbols, UL symbols, and flexible symbols, may beconfigured with a cell-specific or common radio resource control (RRC)signal. In addition, information on the type of each symbol mayadditionally be configured with a UE-specific or dedicated RRC signal.The base station informs, by using cell-specific RRC signals, i) theperiod of cell-specific slot configuration, ii) the number of slots withonly DL symbols from the beginning of the period of cell-specific slotconfiguration, iii) the number of DL symbols from the first symbol ofthe slot immediately following the slot with only DL symbols, iv) thenumber of slots with only UL symbols from the end of the period of cellspecific slot configuration, and v) the number of UL symbols from thelast symbol of the slot immediately before the slot with only the ULsymbol. Here, symbols not configured with any one of a UL symbol and aDL symbol are flexible symbols.

When the information on the symbol type is configured with theUE-specific RRC signal, the base station may signal whether the flexiblesymbol is a DL symbol or an UL symbol in the cell-specific RRC signal.In this case, the UE-specific RRC signal can not change a DL symbol or aUL symbol configured with the cell-specific RRC signal into anothersymbol type. The UE-specific RRC signal may signal the number of DLsymbols among the N^(slot) _(symb) symbols of the corresponding slot foreach slot, and the number of UL symbols among the N^(slot) _(symb)symbols of the corresponding slot. In this case, the DL symbol of theslot may be continuously configured with the first symbol to the i-thsymbol of the slot. In addition, the UL symbol of the slot may becontinuously configured with the j-th symbol to the last symbol of theslot (where i <j). In the slot, symbols not configured with any one of aUL symbol and a DL symbol are flexible symbols.

FIG. 3 is a diagram for explaining a physical channel used in a 3GPPsystem (e.g., NR) and a typical signal transmission method using thephysical channel.

If the power of the UE is turned on or the UE camps on a new cell, theUE performs an initial cell search (S101). Specifically, the UE maysynchronize with the BS in the initial cell search. For this, the UE mayreceive a primary synchronization signal (PSS) and a secondarysynchronization signal (SSS) from the base station to synchronize withthe base station, and obtain information such as a cell ID. Thereafter,the UE can receive the physical broadcast channel from the base stationand obtain the broadcast information in the cell.

Upon completion of the initial cell search, the UE receives a physicaldownlink shared channel (PDSCH) according to the physical downlinkcontrol channel (PDCCH) and information in the PDCCH, so that the UE canobtain more specific system information than the system informationobtained through the initial cell search (S102). Herein, the systeminformation received by the UE is cell-common system information fornormal operating of the UE in a physical layer in radio resource control(RRC) and is referred to remaining system information, or systeminformation block (SIB) 1 is called.

When the UE initially accesses the base station or does not have radioresources for signal transmission (i.e. the UE at RRC IDLE mode), the UEmay perform a random access procedure on the base station (operationsS103 to S106). First, the UE can transmit a preamble through a physicalrandom access channel (PRACH) (S103) and receive a response message forthe preamble from the base station through the PDCCH and thecorresponding PDSCH (S104). When a valid random access response messageis received by the UE, the UE transmits data including the identifier ofthe UE and the like to the base station through a physical uplink sharedchannel (PUSCH) indicated by the UL grant transmitted through the PDCCHfrom the base station (S105). Next, the UE waits for reception of thePDCCH as an indication of the base station for collision resolution. Ifthe UE successfully receives the PDCCH through the identifier of the UE(S106), the random access process is terminated. The UE may obtainUE-specific system information for normal operating of the UE in thephysical layer in RRC layer during a random access process. When the UEobtain the UE-specific system information, the UE enter RRC connectingmode (RRC_CONNECTED mode).

The RRC layer is used for generating or managing message for controllingconnection between the UE and radio access network (RAN). In moredetail, the base station and the UE, in the RRC layer, may performbroadcasting cell system information required by every UE in the cell,managing mobility and handover, measurement report of the UE, storagemanagement including UE capability management and device management. Ingeneral, the RRC signal is not changed and maintained quite longinterval since a period of an update of a signal delivered in the RRClayer is longer than a transmission time interval (TTI) in physicallayer.

After the above-described procedure, the UE receives PDCCH/PDSCH (S107)and transmits a physical uplink shared channel (PUSCH)/physical uplinkcontrol channel (PUCCH) (S108) as a general UL/DL signal transmissionprocedure. In particular, the UE may receive downlink controlinformation (DCI) through the PDCCH. The DCI may include controlinformation such as resource allocation information for the UE. Also,the format of the DCI may vary depending on the intended use. The uplinkcontrol information (UCI) that the UE transmits to the base stationthrough UL includes a DL/UL ACK/NACK signal, a channel quality indicator(CQI), a precoding matrix index (PMI), a rank indicator (RI), and thelike. Here, the CQI, PMI, and RI may be included in channel stateinformation (CSI). In the 3GPP NR system, the UE may transmit controlinformation such as HARQ-ACK and CSI described above through the PUSCHand/or PUCCH.

FIG. 4 illustrates an SS/PBCH block for initial cell access in a 3GPP NRsystem.

When the power is turned on or wanting to access a new cell, the UE mayobtain time and frequency synchronization with the cell and perform aninitial cell search procedure. The UE may detect a physical cellidentity N^(cell) _(ID) of the cell during a cell search procedure. Forthis, the UE may receive a synchronization signal, for example, aprimary synchronization signal (PSS) and a secondary synchronizationsignal (SSS), from a base station, and synchronize with the basestation. In this case, the UE can obtain information such as a cellidentity (ID).

Referring to FIG. 4A, a synchronization signal (SS) will be described inmore detail. The synchronization signal can be classified into PSS andSSS. The PSS may be used to obtain time region synchronization and/orfrequency region synchronization, such as OFDM symbol synchronizationand slot synchronization. The SSS can be used to obtain framesynchronization and cell group ID. Referring to FIG. 4A and Table 1, theSS/PBCH block can be configured with consecutive 20 RBs (=240subcarriers) in the frequency axis, and can be configured withconsecutive 4 OFDM symbols in the time axis. In this case, in theSS/PBCH block, the PSS is transmitted in the first OFDM symbol and theSSS is transmitted in the third OFDM symbol through the 56th to 182thsubcarriers. Here, the lowest subcarrier index of the SS/PBCH block isnumbered from 0. In the first OFDM symbol in which the PSS istransmitted, the base station does not transmit a signal through theremaining subcarriers, i.e., 0th to 55th and 183th to 239th subcarriers.In addition, in the third OFDM symbol in which the SSS is transmitted,the base station does not transmit a signal through 48th to 55th and183th to 191th subcarriers. The base station transmits a physicalbroadcast channel (PBCH) through the remaining RE except for the abovesignal in the SS/PBCH block.

TABLE 1 OFDM symbol number l relative Subcarrier number k Channel to thestart of an relative to the start or signal SS/PBCH block of an SS/PBCHblock PSS 0 56, 57, . . . , 182 SSS 2 56, 57, . . . , 182 Set to 0 0 0,1, . . . , 55, 183, 184, . . . , 239 2 48, 49, . . . , 55, 183, 184, . .. , 191 PBCH 1, 3 0, 1, . . . , 239 2 0, 1, . . . , 47, 192, 193, . . ., 239 DM-RS for 1, 3 0 + v, 4 + v, 8 + v, . . . , 236 + v PBCH 2 0 + v,4 + v, 8 + v, . . . , 44 + v 192 + v, 196 + v, . . . , 236 + v

The SS allows a total of 1008 unique physical layer cell IDs to begrouped into 336 physical-layer cell-identifier groups, each groupincluding three unique identifiers, through a combination of three PSSsand SSSs, specifically, such that each physical layer cell ID is to beonly a part of one physical-layer cell-identifier group. Therefore, thephysical layer cell ID N^(cell) _(ID)=3N⁽¹⁾ _(ID)+N⁽²⁾ _(ID) can beuniquely defined by the index N⁽¹⁾ _(ID) ranging from 0 to 335indicating a physical-layer cell-identifier group and the index N⁽²⁾_(ID) ranging from 0 to 2 indicating a physical-layer identifier in thephysical-layer cell-identifier group. The UE may detect the PSS andidentify one of the three unique physical-layer identifiers. Inaddition, the UE can detect the SSS and identify one of the 336 physicallayer cell IDs associated with the physical-layer identifier. In thiscase, the sequence d_(PSS) (n) of the PSS is as follows.

d_(PSS) (n)=1−2x (m)

m=(n+43N⁽²⁾ _(ID)) mod 127

0≤n<127

Here, x (i+7)=(x (i+4)+x (i)) mod 2 and is given as

[x(6) x(5) x(4) x(3) x(2) x(1) x(0)]=[1 1 1 0 1 1 0]

Further, the sequence dsss (n) of the SSS is as follows.

d_(SSS) (n)=[1−2x ₀((n+m ₀) mod 127] [1−2x _(i) ((n+m ₁) mod 127]

m₀=15 floor (N⁽¹⁾ _(ID)/112)+5N⁽²⁾ _(ID)

m1=N⁽¹⁾ _(ID) mod 112

0≤n<127

Here, x₀(i+7)=(x₀(i+4)+x₀(i)) mod 2

x₁(i+7)=(x₁(i+1)+x₁ (i)) mod 2 and is given as

[x₀(6) x₀(5) x₀(4) x₀(3) x₀(2) x₀(1) x₀(0)]=[0 0 0 0 0 0 1]

[x₁(6) x₁(5) x₁(4) x₁(3) x₁(2) x₁(1) x₁(0)]=[0 0 0 0 0 0 1]

A radio frame with a 10 ms length may be divided into two half frameswith a 5 ms length. Referring to FIG. 4B, a description will be made ofa slot in which SS/PBCH blocks are transmitted in each half frame. Aslot in which the SS/PBCH block is transmitted may be any one of thecases A, B, C, D, and E. In the case A, the subcarrier spacing is 15 kHzand the starting time point of the SS/PBCH block is the ({2, 8}+14*n)-thsymbol. In this case, n=0 or 1 at a carrier frequency of 3 GHz or less.In addition, it may be n=0, 1, 2, 3 at carrier frequencies above 3 GHzand below 6 GHz. In the case B, the subcarrier spacing is 30 kHz and thestarting time point of the SS/PBCH block is {4, 8, 16, 20}+28*n. In thiscase, n=0 at a carrier frequency of 3 GHz or less. In addition, it maybe n=0, 1 at carrier frequencies above 3 GHz and below 6 GHz. In thecase C, the subcarrier spacing is 30 kHz and the starting time point ofthe SS/PBCH block is the ({2, 8}+14*n)-th symbol. In this case, n=0 or 1at a carrier frequency of 3 GHz or less. In addition, it may be n=0, 1,2, 3 at carrier frequencies above 3 GHz and below 6 GHz. In the case D,the subcarrier spacing is 120 kHz and the starting time point of theSS/PBCH block is the ({4, 8, 16, 20}+28*n)-th symbol. In this case, at acarrier frequency of 6 GHz or more, n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11,12, 13, 15, 16, 17, 18. In the case E, the subcarrier spacing is 240 kHzand the starting time point of the SS/PBCH block is the ({8, 12, 16, 20,32, 36, 40, 44}+56*n)-th symbol. In this case, at a carrier frequency of6 GHz or more, n=0, 1, 2, 3, 5, 6, 7, 8.

FIG. 5 illustrates a procedure for transmitting control information anda control channel in a 3GPP NR system. Referring to FIG. 5A, the basestation may add a cyclic redundancy check (CRC) masked (e.g., an XORoperation) with a radio network temporary identifier (RNTI) to controlinformation (e.g., downlink control information (DCI)) (S202). The basestation may scramble the CRC with an RNTI value determined according tothe purpose/target of each control information. The common RNTI used byone or more UEs can include at least one of a system information RNTI(SI-RNTI), a paging RNTI (P-RNTI), a random access RNTI (RA-RNTI), and atransmit power control RNTI (TPC-RNTI). In addition, the UE-specificRNTI may include at least one of a cell temporary RNTI (C-RNTI), and theCS-RNTI. Thereafter, the base station may perform rate-matching (S206)according to the amount of resource(s) used for PDCCH transmission afterperforming channel encoding (e.g., polar coding) (S204). Thereafter, thebase station may multiplex the DCI(s) based on the control channelelement (CCE) based PDCCH structure (S208). In addition, the basestation may apply an additional process (S210) such as scrambling,modulation (e.g., QPSK), interleaving, and the like to the multiplexedDCI(s), and then map the DCI(s) to the resource to be transmitted. TheCCE is a basic resource unit for the PDCCH, and one CCE may include aplurality (e.g., six) of resource element groups (REGs). One REG may beconfigured with a plurality (e.g., 12) of REs. The number of CCEs usedfor one PDCCH may be defined as an aggregation level. In the 3GPP NRsystem, an aggregation level of 1, 2, 4, 8, or 16 may be used. FIG. 5Bis a diagram related to a CCE aggregation level and the multiplexing ofa PDCCH and illustrates the type of a CCE aggregation level used for onePDCCH and CCE(s) transmitted in the control area according thereto.

FIG. 6 illustrates a control resource set (CORESET) in which a physicaldownlink control channel (PUCCH) may be transmitted in a 3GPP NR system.

The CORESET is a time-frequency resource in which PDCCH, that is, acontrol signal for the UE, is transmitted. In addition, a search spaceto be described later may be mapped to one CORESET. Therefore, the UEmay monitor the time-frequency region designated as CORESET instead ofmonitoring all frequency bands for PDCCH reception, and decode the PDCCHmapped to CORESET. The base station may configure one or more CORESETsfor each cell to the UE. The CORESET may be configured with up to threeconsecutive symbols on the time axis. In addition, the CORESET may beconfigured in units of six consecutive PRBs on the frequency axis. Inthe embodiment of FIG. 5, CORESET# 1 is configured with consecutivePRBs, and CORESET# 2 and CORESET# 3 are configured with discontinuousPRBs. The CORESET can be located in any symbol in the slot. For example,in the embodiment of FIG. 5, CORESET# 1 starts at the first symbol ofthe slot, CORESET# 2 starts at the fifth symbol of the slot, andCORESET# 9 starts at the ninth symbol of the slot.

FIG. 7 illustrates a method for setting a PDCCH search space in a 3GPPNR system.

In order to transmit the PDCCH to the UE, each CORESET may have at leastone search space. In the embodiment of the present disclosure, thesearch space is a set of all time-frequency resources (hereinafter,PDCCH candidates) through which the PDCCH of the UE is capable of beingtransmitted. The search space may include a common search space that theUE of the 3GPP NR is required to commonly search and a UE-specific or aUE-specific search space that a specific UE is required to search. Inthe common search space, UE may monitor the PDCCH that is set so thatall UEs in the cell belonging to the same base station commonly search.In addition, the UE-specific search space may be set for each UE so thatUEs monitor the PDCCH allocated to each UE at different search spaceposition according to the UE. In the case of the UE-specific searchspace, the search space between the UEs may be partially overlapped andallocated due to the limited control area in which the PDCCH may beallocated. Monitoring the PDCCH includes blind decoding for PDCCHcandidates in the search space. When the blind decoding is successful,it may be expressed that the PDCCH is (successfully) detected/receivedand when the blind decoding fails, it may be expressed that the PDCCH isnot detected/not received, or is not successfully detected/received.

For convenience of explanation, a PDCCH scrambled with a group common(GC) RNTI previously known to one or more UEs so as to transmit DLcontrol information to the one or more UEs is referred to as a groupcommon (GC) PDCCH or a common PDCCH. In addition, a PDCCH scrambled witha specific-terminal RNTI that a specific UE already knows so as totransmit UL scheduling information or DL scheduling information to thespecific UE is referred to as a specific-UE PDCCH. The common PDCCH maybe included in a common search space, and the UE-specific PDCCH may beincluded in a common search space or a UE-specific PDCCH.

The base station may signal each UE or UE group through a PDCCH aboutinformation (i.e., DL Grant) related to resource allocation of a pagingchannel (PCH) and a downlink-shared channel (DL-SCH) that are atransmission channel or information (i.e., UL grant) related to resourceallocation of a uplink-shared channel (UL-SCH) and a hybrid automaticrepeat request (HARQ). The base station may transmit the PCH transportblock and the DL-SCH transport block through the PDSCH. The base stationmay transmit data excluding specific control information or specificservice data through the PDSCH. In addition, the UE may receive dataexcluding specific control information or specific service data throughthe PDSCH.

The base station may include, in the PDCCH, information on to which UE(one or a plurality of UEs) PDSCH data is transmitted and how the PDSCHdata is to be received and decoded by the corresponding UE, and transmitthe PDCCH. For example, it is assumed that the DCI transmitted on aspecific PDCCH is CRC masked with an RNTI of “A”, and the DCI indicatesthat PDSCH is allocated to a radio resource (e.g., frequency location)of “B” and indicates transmission format information (e.g., transportblock size, modulation scheme, coding information, etc.) of “C”. The UEmonitors the PDCCH using the RNTI information that the UE has. In thiscase, if there is a UE which performs blind decoding the PDCCH using the“A” RNTI, the UE receives the PDCCH, and receives the PDSCH indicated by“B” and “C” through the received PDCCH information.

Table 2 shows an embodiment of a physical uplink control channel (PUCCH)used in a wireless communication system.

TABLE 2 Length in PUCCH OFDM Number format symbols of bits 0 1-2  ≤2 14-14 ≤2 2 1-2  >2 3 4-14 >2 4 4-14 >2

The PUCCH may be used to transmit the following UL control information(UCI).

Scheduling Request (SR): Information used for requesting a UL UL-SCHresource.

HARQ-ACK: A Response to PDCCH (indicating DL SPS release) and/or aresponse to DL transport block (TB) on PDSCH. HARQ-ACK indicates whetherinformation transmitted on the PDCCH or PDSCH is received. The HARQ-ACKresponse includes positive ACK (simply ACK), negative ACK (hereinafterNACK), Discontinuous Transmission (DTX), or NACK/DTX. Here, the termHARQ-ACK is used mixed with HARQ-ACK/NACK and ACK/NACK. In general, ACKmay be represented by bit value 1 and NACK may be represented by bitvalue 0.

Channel State Information (CSI): Feedback information on the DL channel.The UE generates it based on the CSI-Reference Signal (RS) transmittedby the base station. Multiple Input Multiple Output (MIMO)-relatedfeedback information includes a Rank Indicator (RI) and a PrecodingMatrix Indicator (PMI). CSI can be divided into CSI part 1 and CSI part2 according to the information indicated by CSI.

In the 3GPP NR system, five PUCCH formats may be used to support variousservice scenarios, various channel environments, and frame structures.

PUCCH format 0 is a format capable of delivering 1-bit or 2-bit HARQ-ACKinformation or SR. PUCCH format 0 can be transmitted through one or twoOFDM symbols on the time axis and one PRB on the frequency axis. WhenPUCCH format 0 is transmitted in two OFDM symbols, the same sequence onthe two symbols may be transmitted through different RBs. In this case,the sequence may be a sequence cyclic shifted (CS) from a base sequenceused in PUCCH format 0. Through this, the UE may obtain a frequencydiversity gain. In more detail, the UE may determine a cyclic shift (CS)value m_(cs) according to Mbit bit UCI (M_(bit)=1 or 2). In addition,the base sequence having the length of 12 may be transmitted by mappinga cyclic shifted sequence based on a predetermined CS value m_(cs) toone OFDM symbol and 12 REs of one RB. When the number of cyclic shiftsavailable to the UE is 12 and M_(bit)=1, 1 bit UCI 0 and 1 may be mappedto two cyclic shifted sequences having a difference of 6 in the cyclicshift value, respectively. In addition, when M_(bit)=2, 2 bit UCI 00,01, 11, and 10 may be mapped to four cyclic shifted sequences having adifference of 3 in cyclic shift values, respectively.

PUCCH format 1 may deliver 1-bit or 2-bit HARQ-ACK information or SR.PUCCH format 1 maybe transmitted through consecutive OFDM symbols on thetime axis and one PRB on the frequency axis. Here, the number of OFDMsymbols occupied by PUCCH format 1 may be one of 4 to 14. Morespecifically, UCI, which is M_(bit)=1, may be BPSK-modulated. The UE maymodulate UCI, which is M_(bit)=2, with quadrature phase shift keying(QPSK). A signal is obtained by multiplying a modulated complex valuedsymbol d(0) by a sequence of length 12. In this case, the sequence maybe a base sequence used for PUCCH format 0. The UE spreads theeven-numbered OFDM symbols to which PUCCH format 1 is allocated throughthe time axis orthogonal cover code (OCC) to transmit the obtainedsignal. PUCCH format 1 determines the maximum number of different UEsmultiplexed in the one RB according to the length of the OCC to be used.A demodulation reference signal (DMRS) may be spread with OCC and mappedto the odd-numbered OFDM symbols of PUCCH format 1.

PUCCH format 2 may deliver UCI exceeding 2 bits. PUCCH format 2 may betransmitted through one or two OFDM symbols on the time axis and one ora plurality of RBs on the frequency axis. When PUCCH format 2 istransmitted in two OFDM symbols, the sequences which are transmitted indifferent RBs through the two OFDM symbols may be same each other. Here,the sequence may be a plurality of modulated complex valued symbolsd(0), . . . , d(M_(symbol)−1). Here, M_(symbol) may be M_(bit)/2.Through this, the UE may obtain a frequency diversity gain. Morespecifically, M_(bit) bit UCI (M_(bit)>2) is bit-level scrambled, QPSKmodulated, and mapped to RB(s) of one or two OFDM symbol(s). Here, thenumber of RBs may be one of 1 to 16.

PUCCH format 3 or PUCCH format 4 may deliver UCI exceeding 2 bits. PUCCHformat 3 or PUCCH format 4 may be transmitted through consecutive OFDMsymbols on the time axis and one PRB on the frequency axis. The numberof OFDM symbols occupied by PUCCH format 3 or PUCCH format 4 may be oneof 4 to 14. Specifically, the UE modulates M_(bit) bits UCI (Mbit>2)with n/2-Binary Phase Shift Keying (BPSK) or QPSK to generate a complexvalued symbol d(0) to d(M_(sy)mb-1). Here, when using n/2-BPSK,M_(symb)=M_(bit), and when using QPSK, M_(symb)=M_(bit)/2. The UE maynot apply block-unit spreading to the PUCCH format 3. However, the UEmay apply block-unit spreading to one RB (i.e., 12 subcarriers) usingPreDFT-OCC of a length of such that PUCCH format 4 may have two or fourmultiplexing capacities. The UE performs transmit precoding (orDFT-precoding) on the spread signal and maps it to each RE to transmitthe spread signal.

In this case, the number of RBs occupied by PUCCH format 2, PUCCH format3, or PUCCH format 4 may be determined according to the length andmaximum code rate of the UCI transmitted by the UE. When the UE usesPUCCH format 2, the UE may transmit HARQ-ACK information and CSIinformation together through the PUCCH. When the number of RBs that theUE may transmit is greater than the maximum number of RBs that PUCCHformat 2, or PUCCH format 3, or PUCCH format 4 may use, the UE maytransmit only the remaining UCI information without transmitting someUCI information according to the priority of the UCI information.

PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configuredthrough the RRC signal to indicate frequency hopping in a slot. Whenfrequency hopping is configured, the index of the RB to be frequencyhopped may be configured with an RRC signal. When PUCCH format 1, PUCCHformat 3, or PUCCH format 4 is transmitted through N OFDM symbols on thetime axis, the first hop may have floor (N/2) OFDM symbols and thesecond hop may have ceiling(N/2) OFDM symbols.

PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured tobe repeatedly transmitted in a plurality of slots. In this case, thenumber K of slots in which the PUCCH is repeatedly transmitted may beconfigured by the RRC signal. The repeatedly transmitted PUCCHs muststart at an OFDM symbol of the constant position in each slot, and havethe constant length. When one OFDM symbol among OFDM symbols of a slotin which a UE should transmit a PUCCH is indicated as a DL symbol by anRRC signal, the UE may not transmit the PUCCH in a corresponding slotand delay the transmission of the PUCCH to the next slot to transmit thePUCCH.

Meanwhile, in the 3GPP NR system, a UE may performtransmission/reception using a bandwidth equal to or less than thebandwidth of a carrier (or cell). For this, the UE may receive theBandwidth part (BWP) configured with a continuous bandwidth of some ofthe carrier's bandwidth. A UE operating according to TDD or operating inan unpaired spectrum can receive up to four DL/UL BWP pairs in onecarrier (or cell). In addition, the UE may activate one DL/UL BWP pair.A UE operating according to FDD or operating in paired spectrum canreceive up to four DL BWPs on a DL carrier (or cell) and up to four ULBWPs on a UL carrier (or cell). The UE may activate one DL BWP and oneUL BWP for each carrier (or cell). The UE may not perform reception ortransmission in a time-frequency resource other than the activated BWP.The activated BWP may be referred to as an active BWP.

The base station may indicate the activated BWP among the BWPsconfigured by the UE through downlink control information (DCI). The BWPindicated through the DCI is activated and the other configured BWP(s)are deactivated. In a carrier (or cell) operating in TDD, the basestation may include, in the DCI for scheduling PDSCH or PUSCH, abandwidth part indicator (BPI) indicating the BWP to be activated tochange the DL/UL BWP pair of the UE. The UE may receive the DCI forscheduling the PDSCH or PUSCH and may identify the DL/UL BWP pairactivated based on the BPI. For a DL carrier (or cell) operating in anFDD, the base station may include a BPI indicating the BWP to beactivated in the DCI for scheduling PDSCH so as to change the DL BWP ofthe UE. For a UL carrier (or cell) operating in an FDD, the base stationmay include a BPI indicating the BWP to be activated in the DCI forscheduling PUSCH so as to change the UL BWP of the UE.

FIG. 8 is a conceptual diagram illustrating carrier aggregation.

The carrier aggregation is a method in which the UE uses a plurality offrequency blocks or cells (in the logical sense) configured with ULresources (or component carriers) and/or DL resources (or componentcarriers) as one large logical frequency band in order for a wirelesscommunication system to use a wider frequency band. One componentcarrier may also be referred to as a term called a Primary cell (PCell)or a Secondary cell (SCell), or a Primary SCell (PScell). However,hereinafter, for convenience of description, the term “componentcarrier” is used.

Referring to FIG. 8, as an example of a 3GPP NR system, the entiresystem band may include up to 16 component carriers, and each componentcarrier may have a bandwidth of up to 400 MHz. The component carrier mayinclude one or more physically consecutive subcarriers. Although it isshown in FIG. 8 that each of the component carriers has the samebandwidth, this is merely an example, and each component carrier mayhave a different bandwidth. Also, although each component carrier isshown as being adjacent to each other in the frequency axis, thedrawings are shown in a logical concept, and each component carrier maybe physically adjacent to one another, or may be spaced apart.

Different center frequencies may be used for each component carrier.Also, one common center frequency may be used in physically adjacentcomponent carriers. Assuming that all the component carriers arephysically adjacent in the embodiment of FIG. 8, center frequency A maybe used in all the component carriers. Further, assuming that therespective component carriers are not physically adjacent to each other,center frequency A and the center frequency B can be used in each of thecomponent carriers.

When the total system band is extended by carrier aggregation, thefrequency band used for communication with each UE can be defined inunits of a component carrier. UE A may use 100 MHz, which is the totalsystem band, and performs communication using all five componentcarriers. UEs B₁˜B₅ can use only a 20 MHz bandwidth and performcommunication using one component carrier. UEs C₁ and C₂ may use a 40MHz bandwidth and perform communication using two component carriers,respectively. The two component carriers may be logically/physicallyadjacent or non-adjacent. UE C₁ represents the case of using twonon-adjacent component carriers, and UE C₂ represents the case of usingtwo adjacent component carriers.

FIG. 9 is a drawing for explaining single carrier communication andmultiple carrier communication. Particularly, FIG. 9(a) shows a singlecarrier subframe structure and FIG. 9(b) shows a multi-carrier subframestructure.

Referring to FIG. 9(a), in an FDD mode, a general wireless communicationsystem may perform data transmission or reception through one DL bandand one UL band corresponding thereto. In another specific embodiment,in a TDD mode, the wireless communication system may divide a radioframe into a UL time unit and a DL time unit in a time region, andperform data transmission or reception through a UL/DL time unit.Referring to FIG. 9(b), three 20 MHz component carriers (CCs) can beaggregated into each of UL and DL, so that a bandwidth of 60 MHz can besupported. Each CC may be adjacent or non-adjacent to one another in thefrequency region. FIG. 9(b) shows a case where the bandwidth of the ULCC and the bandwidth of the DL CC are the same and symmetric, but thebandwidth of each CC can be determined independently. In addition,asymmetric carrier aggregation with different number of UL CCs and DLCCs is possible. A DL/UL CC allocated/configured to a specific UEthrough RRC may be called as a serving DL/UL CC of the specific UE.

The base station may perform communication with the UE by activatingsome or all of the serving CCs of the UE or deactivating some CCs. Thebase station can change the CC to be activated/deactivated, and changethe number of CCs to be activated/deactivated. If the base stationallocates a CC available for the UE as to be cell-specific orUE-specific, at least one of the allocated CCs can be deactivated,unless the CC allocation for the UE is completely reconfigured or the UEis handed over. One CC that is not deactivated by the UE is called as aPrimary CC (PCC) or a primary cell (PCell), and a CC that the basestation can freely activate/deactivate is called as a Secondary CC (SCC)or a secondary cell (SCell).

Meanwhile, 3GPP NR uses the concept of a cell to manage radio resources.A cell is defined as a combination of DL resources and UL resources,that is, a combination of DL CC and UL CC. A cell may be configured withDL resources alone, or a combination of DL resources and UL resources.When the carrier aggregation is supported, the linkage between thecarrier frequency of the DL resource (or DL CC) and the carrierfrequency of the UL resource (or UL CC) may be indicated by systeminformation. The carrier frequency refers to the center frequency ofeach cell or CC. A cell corresponding to the PCC is referred to as aPCell, and a cell corresponding to the SCC is referred to as an SCell.The carrier corresponding to the PCell in the DL is the DL PCC, and thecarrier corresponding to the PCell in the UL is the UL PCC. Similarly,the carrier corresponding to the SCell in the DL is the DL SCC and thecarrier corresponding to the SCell in the UL is the UL SCC. According toUE capability, the serving cell(s) may be configured with one PCell andzero or more SCells. In the case of UEs that are in the RRC_CONNECTEDstate but not configured for carrier aggregation or that do not supportcarrier aggregation, there is only one serving cell configured only withPCell.

As mentioned above, the term “cell” used in carrier aggregation isdistinguished from the term “cell” which refers to a certaingeographical area in which a communication service is provided by onebase station or one antenna group. That is, one component carrier mayalso be referred to as a scheduling cell, a scheduled cell, a primarycell (PCell), a secondary cell (SCell), or a primary SCell (PScell).However, in order to distinguish between a cell referring to a certaingeographical area and a cell of carrier aggregation, in the presentdisclosure, a cell of a carrier aggregation is referred to as a CC, anda cell of a geographical area is referred to as a cell.

FIG. 10 is a diagram showing an example in which a cross carrierscheduling technique is applied. When cross carrier scheduling is set,the control channel transmitted through the first CC may schedule a datachannel transmitted through the first CC or the second CC using acarrier indicator field (CIF). The CIF is included in the DCI. In otherwords, a scheduling cell is set, and the DL grant/UL grant transmittedin the PDCCH area of the scheduling cell schedules the PDSCH/PUSCH ofthe scheduled cell. That is, a search area for the plurality ofcomponent carriers exists in the PDCCH area of the scheduling cell. APCell may be basically a scheduling cell, and a specific SCell may bedesignated as a scheduling cell by an upper layer.

In the embodiment of FIG. 10, it is assumed that three DL CCs aremerged. Here, it is assumed that DL component carrier # 0 is DL PCC (orPCell), and DL component carrier # 1 and DL component carrier # 2 are DLSCCs (or SCell). In addition, it is assumed that the DL PCC is set tothe PDCCH monitoring CC. When cross-carrier scheduling is not configuredby UE-specific (or UE-group-specific or cell-specific) higher layersignaling, a CIF is disabled, and each DL CC can transmit only a PDCCHfor scheduling its PDSCH without the CIF according to an NR PDCCH rule(non-cross-carrier scheduling, self-carrier scheduling). Meanwhile, ifcross-carrier scheduling is configured by UE-specific (orUE-group-specific or cell-specific) higher layer signaling, a CIF isenabled, and a specific CC (e.g., DL PCC) may transmit not only thePDCCH for scheduling the PDSCH of the DL CC A using the CIF but also thePDCCH for scheduling the PDSCH of another CC (cross-carrier scheduling).On the other hand, a PDCCH is not transmitted in another DL CC.Accordingly, the UE monitors the PDCCH not including the CIF to receivea self-carrier scheduled PDSCH depending on whether the cross-carrierscheduling is configured for the UE, or monitors the PDCCH including theCIF to receive the cross-carrier scheduled PDSCH.

On the other hand, FIGS. 9 and 10 illustrate the subframe structure ofthe 3GPP LTE-A system, and the same or similar configuration may beapplied to the 3GPP NR system. However, in the 3GPP NR system, thesubframes of FIGS. 9 and 10 may be replaced with slots.

FIG. 11 is a block diagram showing the configurations of a UE and a basestation according to an embodiment of the present disclosure. In anembodiment of the present disclosure, the UE may be implemented withvarious types of wireless communication devices or computing devicesthat are guaranteed to be portable and mobile. The UE may be referred toas a User Equipment (UE), a Station (STA), a Mobile Subscriber (MS), orthe like. In addition, in an embodiment of the present disclosure, thebase station controls and manages a cell (e.g., a macro cell, a femtocell, a pico cell, etc.) corresponding to a service area, and performsfunctions of a signal transmission, a channel designation, a channelmonitoring, a self diagnosis, a relay, or the like. The base station maybe referred to as next Generation NodeB (gNB) or Access Point (AP).

As shown in the drawing, a UE 100 according to an embodiment of thepresent disclosure may include a processor 110, a communication module120, a memory 130, a user interface 140, and a display unit 150.

First, the processor 110 may execute various instructions or programsand process data within the UE 100. In addition, the processor 110 maycontrol the entire operation including each unit of the UE 100, and maycontrol the transmission/reception of data between the units. Here, theprocessor 110 may be configured to perform an operation according to theembodiments described in the present disclosure. For example, theprocessor 110 may receive slot configuration information, determine aslot configuration based on the slot configuration information, andperform communication according to the determined slot configuration.

Next, the communication module 120 may be an integrated module thatperforms wireless communication using a wireless communication networkand a wireless LAN access using a wireless LAN. For this, thecommunication module 120 may include a plurality of network interfacecards (NICs) such as cellular communication interface cards 121 and 122and an unlicensed band communication interface card 123 in an internalor external form. In the drawing, the communication module 120 is shownas an integral integration module, but unlike the drawing, each networkinterface card can be independently arranged according to a circuitconfiguration or usage.

The cellular communication interface card 121 may transmit or receive aradio signal with at least one of the base station 200, an externaldevice, and a server by using a mobile communication network and providea cellular communication service in a first frequency band based on theinstructions from the processor 110. According to an embodiment, thecellular communication interface card 121 may include at least one NICmodule using a frequency band of less than 6 GHz. At least one NICmodule of the cellular communication interface card 121 mayindependently perform cellular communication with at least one of thebase station 200, an external device, and a server in accordance withcellular communication standards or protocols in the frequency bandsbelow 6 GHz supported by the corresponding NIC module.

The cellular communication interface card 122 may transmit or receive aradio signal with at least one of the base station 200, an externaldevice, and a server by using a mobile communication network and providea cellular communication service in a second frequency band based on theinstructions from the processor 110. According to an embodiment, thecellular communication interface card 122 may include at least one NICmodule using a frequency band of more than 6 GHz. At least one NICmodule of the cellular communication interface card 122 mayindependently perform cellular communication with at least one of thebase station 200, an external device, and a server in accordance withcellular communication standards or protocols in the frequency bands of6 GHz or more supported by the corresponding NIC module.

The unlicensed band communication interface card 123 transmits orreceives a radio signal with at least one of the base station 200, anexternal device, and a server by using a third frequency band which isan unlicensed band, and provides an unlicensed band communicationservice based on the instructions from the processor 110. The unlicensedband communication interface card 123 may include at least one NICmodule using an unlicensed band. For example, the unlicensed band may bea band of 2.4 GHz or 5 GHz. At least one NIC module of the unlicensedband communication interface card 123 may independently or dependentlyperform wireless communication with at least one of the base station200, an external device, and a server according to the unlicensed bandcommunication standard or protocol of the frequency band supported bythe corresponding NIC module.

The memory 130 stores a control program used in the UE 100 and variouskinds of data therefor. Such a control program may include a prescribedprogram required for performing wireless communication with at least oneamong the base station 200, an external device, and a server.

Next, the user interface 140 includes various kinds of input/outputmeans provided in the UE 100. In other words, the user interface 140 mayreceive a user input using various input means, and the processor 110may control the UE 100 based on the received user input. In addition,the user interface 140 may perform an output based on instructions fromthe processor 110 using various kinds of output means.

Next, the display unit 150 outputs various images on a display screen.The display unit 150 may output various display objects such as contentexecuted by the processor 110 or a user interface based on controlinstructions from the processor 110.

In addition, the base station 200 according to an embodiment of thepresent disclosure may include a processor 210, a communication module220, and a memory 230.

First, the processor 210 may execute various instructions or programs,and process internal data of the base station 200. In addition, theprocessor 210 may control the entire operations of units in the basestation 200, and control data transmission and reception between theunits. Here, the processor 210 may be configured to perform operationsaccording to embodiments described in the present disclosure. Forexample, the processor 210 may signal slot configuration and performcommunication according to the signaled slot configuration.

Next, the communication module 220 may be an integrated module thatperforms wireless communication using a wireless communication networkand a wireless LAN access using a wireless LAN. For this, thecommunication module 120 may include a plurality of network interfacecards such as cellular communication interface cards 221 and 222 and anunlicensed band communication interface card 223 in an internal orexternal form. In the drawing, the communication module 220 is shown asan integral integration module, but unlike the drawing, each networkinterface card can be independently arranged according to a circuitconfiguration or usage.

The cellular communication interface card 221 may transmit or receive aradio signal with at least one of the UE 100, an external device, and aserver by using a mobile communication network and provide a cellularcommunication service in the first frequency band based on theinstructions from the processor 210. According to an embodiment, thecellular communication interface card 221 may include at least one NICmodule using a frequency band of less than 6 GHz. The at least one NICmodule of the cellular communication interface card 221 mayindependently perform cellular communication with at least one of the UE100, an external device, and a server in accordance with the cellularcommunication standards or protocols in the frequency bands less than 6GHz supported by the corresponding NIC module.

The cellular communication interface card 222 may transmit or receive aradio signal with at least one of the UE 100, an external device, and aserver by using a mobile communication network and provide a cellularcommunication service in the second frequency band based on theinstructions from the processor 210. According to an embodiment, thecellular communication interface card 222 may include at least one NICmodule using a frequency band of 6 GHz or more. The at least one NICmodule of the cellular communication interface card 222 mayindependently perform cellular communication with at least one of thebase station 100, an external device, and a server in accordance withthe cellular communication standards or protocols in the frequency bands6 GHz or more supported by the corresponding NIC module.

The unlicensed band communication interface card 223 transmits orreceives a radio signal with at least one of the base station 100, anexternal device, and a server by using the third frequency band which isan unlicensed band, and provides an unlicensed band communicationservice based on the instructions from the processor 210. The unlicensedband communication interface card 223 may include at least one NICmodule using an unlicensed band. For example, the unlicensed band may bea band of 2.4 GHz or 5 GHz. At least one NIC module of the unlicensedband communication interface card 223 may independently or dependentlyperform wireless communication with at least one of the UE 100, anexternal device, and a server according to the unlicensed bandcommunication standards or protocols of the frequency band supported bythe corresponding NIC module.

FIG. 11 is a block diagram illustrating the UE 100 and the base station200 according to an embodiment of the present disclosure, and blocksseparately shown are logically divided elements of a device.Accordingly, the aforementioned elements of the device may be mounted ina single chip or a plurality of chips according to the design of thedevice. In addition, a part of the configuration of the UE 100, forexample, a user interface 140, a display unit 150 and the like may beselectively provided in the UE 100. In addition, the user interface 140,the display unit 150 and the like may be additionally provided in thebase station 200, if necessary.

In order to support a service requiring low latency and highreliability, such as a URLLC service, a UE needs to receive fastretransmission from a base station by transmitting HARQ-ACK as quicklyas possible. However, in 3GPP NR Release 15, only transmission of a

PUCCH including at most one piece of HARQ-ACK information is allowed inone slot. Therefore, the UE uses a scheme of: i) transmitting HARQ-ACKresponses for different PDSCHs in different slots, respectively; or ii)performing multiplexing in one PUCCH. However, i) is not suitable forproviding a low latency time; and in ii), there may be a possibilitythat a problem occurs in the coverage of PUCCH, that is, reliability.Therefore, a method for transmitting multiple PUCCHs, each of whichincludes different HARQ-ACK information, in one slot is being discussed.

Method of Transmitting Multiple PUCCHs in One Slot on the Basis of anIndicator

FIG. 12 is a flowchart illustrating a method of transmitting multiplePUCCHs in one slot on the basis of an indicator according to anembodiment. A base station in FIG. 12 is the same as the base station200 in FIG. 11, and a UE in FIG. 12 is the same as the UE 100 in FIG.11.

Referring to FIG. 12, the base station transmits an indicator to the UE,in S1200. The indicator may indicate values corresponding to the numberof PUCCHs concurrently transmitted in one slot. For example, if it ispossible to transmit up to two PUCCHs concurrently in one slot, theindicator may have two values, for example, 0 or 1. That is, the PUCCHsconcurrently transmitted in one slot are identified by respectiveindicators. If an indicator value of 0 is assigned to one PUCCH, anindicator value of 1 is assigned to the other PUCCH. Similarly, if anindicator value of 1 is assigned to one PUCCH, an indicator value of 0is assigned to the other PUCCH. An identical indicator value cannotcorrespond to different PUCCHs.

For example, referring to FIG. 13, the UE receives at least one PDSCHcorresponding to an indicator value of 0 in a preceding slot 1300, andthen transmits HARQ-ACK relating thereto to the base station via a PUCCH1320 corresponding to the indicator value of 0 in a following slot 1310.The UE receives PDSCHs corresponding to an indicator value of 1 in thepreceding slot 1300, and then transmits HARQ-ACK relating thereto to thebase station via a PUCCH 1330 corresponding to the indicator value of 1in the following slot 1310. That is, multiple PUCCHs 1320 and 1330concurrently transmitted in the following slot 1310 are indexed with 0or 1 by indicators, respectively. If a first PUCCH corresponds to theindicator value of 0, a second PUCCH may correspond to the indicatorvalue of 1, and if the first PUCCH corresponds to the indicator value of1, the second PUCCH may correspond to the indicator value of 0. Theindicators may be used as criteria for collision resolution whenmultiple PUCCH transmissions collide with each other within one slot.

The general range of a value that an indicator may have is as follows.If the number of bits of an indicator is B, and X PUCCHs are to betransmitted in one slot, B=ceil(log2(X)). In this case, the indicatormay indicate one of values of 0, 1, . . . , X−1.

The indicator may be explicitly indicated or may be implicitly inferredfrom other information. If the indicator is implicitly inferred, S1200in FIG. 12 may be omitted. That is, the indicator may not be separatelysignaled, and the UE may implicitly derive the indicator from otherinformation. In this case, the present embodiment corresponds to anembodiment including the remaining operations obtained by excludingS1200.

As an example, the indicator may be transmitted while being included ina PDCCH (or DCI) for scheduling of a first PDSCH or a second PDSCH, inS1205. In this case, the indicator may be referred to as a PDSCH groupindicator or a PDSCH group ID. However, in the present specification, itis denoted as “indicator” for the sake of unification of terms.

As another example, the indicator may be transmitted while beingincluded in RRC signaling.

As another example, the indicator may be information implicitly inferredfrom a value of another field of the PDCCH (or DCI) for scheduling ofthe first PDSCH or the second PDSCH, or from a value of another field ofRRC signaling. A method of implicitly inferring the indicator is similarto implicitly determining a value of an HARQ-ACK multiplexing indicator,which will be described later.

Transmission of the indicator by the base station according to S1200corresponds to the operation of the communication module 220 of FIG. 11,and reception of the indicator by the UE corresponds to the operation ofthe communication module 220 of FIG. 11.

In FIG. 12 again, the base station transmits the first PDSCH and thesecond PDSCH to the UE, in S1205. Here, the first PDSCH and the secondPDSCH may correspond to different types of traffic, for example, eMBBand URLLC. That is, the first PDSCH may be traffic relating to eMBB, andthe second PDSCH may be traffic relating to URLLC. In this embodiment,the description is provided that multiple PDSCHs are transmitted inS1205, but the base station may transmit only one PDSCH to the UE. Thisis because multiple PUCCHs transmitted in the following slot 1310 mayinclude different UCI, such as a scheduling request (SR) transmitted bythe UE regardless of a PDSCH, not necessarily HARQ-ACK associated withthe PDSCH, in the preceding slot 1300. Transmission of the first andsecond PDSCHs by the base station according to S1205 corresponds to theoperation of the communication module 220 of FIG. 11, and reception ofthe first and second PDSCHs by the UE corresponds to the operation ofthe communication module 220 of FIG. 11.

The UE generates a first HARQ-ACK codebook associated with the firstPDSCH and generates a second HARQ-ACK codebook associated with thesecond PDSCH, in S1210. The first HARQ-ACK codebook and the secondHARQ-ACK codebook may be mapped to different PUCCHs in the same slot. Inother words, the first HARQ-ACK codebook and the second HARQ-ACKcodebook may be configured to be transmitted via different PUCCHs withinthe same slot. Here, the first HARQ-ACK codebook is mapped to the firstPUCCH, and the second HARQ-ACK codebook is mapped to the second PUCCH.

When multiple PDSCHs are transmitted, the UE may, as shown in FIG. 13,generate an HARQ-ACK codebook by multiplexing HARQ-ACK of PDSCHs havingthe same indicator value, and then may transmit the generated HARQ-ACKcodebook via the same PUCCH. That is, if different indicator values areused, different PUCCHs may be transmitted in one slot. Referring to FIG.13, the UE may receive two PDSCHs corresponding to the indicator valueof 1 in the preceding slot 1300, may generate an HARQ-ACK codebook bymultiplexing multiple pieces of HARQ-ACK relating thereto, and maytransmit the HARQ-ACK codebook via a PUCCH corresponding to theindicator value of 1 in the following slot 1310. The UE may receive twoPDSCHs corresponding to the indicator value of 0 in the preceding slot1300, may generate an HARQ-ACK codebook by multiplexing multiple piecesof HARQ-ACK relating thereto, and may transmit the HARQ-ACK codebook viaa PUCCH corresponding to the indicator value of 0 in the following slot1310. As a result, a total of two PUCCHs for four PDSCHs are transmittedin one slot.

When multiple PUCCHs are transmitted, a method of generating an HARQ-ACKcodebook for each PUCCH is as follows.

Each HARQ-ACK codebook may be generated in a different manner. Forexample, the first HARQ-ACK codebook may be generated in a semi-staticmanner, and the second HARQ-ACK codebook may be generated in a dynamicmanner.

The UE needs to determine HARQ-ACK bits included in each PUCCH, that is,an HARQ-ACK codebook. In particular, if the UE is configured to use asemi-static HARQ-ACK codebook (or type 1 HARQ-ACK codebook), the UEgenerates a semi-static HARQ-ACK codebook to be transmitted via a PUCCHcorresponding to each indicator value. If the semi-static HARQ-ACKcodebook corresponding to each indicator value is independentlygenerated without a separate definition, a semi-static HARQ-ACK codebookof the same size is transmitted in the same slot via each PUCCH, andthus a problem in that coverage of an uplink PUCCH is limited occurs.

Therefore, the present embodiment provides a method of reducing the sizeof a semi-static HARQ-ACK codebook transmitted via PUCCHs correspondingto different indicator values in one slot.

According to an aspect, the UE includes PDSCH candidates, which arelikely to be transmitted in the preceding half slot of halved slotsobtained by splitting a slot in half, in the semi-static HARQ-ACKcodebook corresponding to the indicator value of 0. In addition, the UEmay include PDSCH candidates, which are likely to be transmitted in thefollowing half slot, in the semi-static HARQ-ACK codebook correspondingto the indicator value of 1. That is, the UE and the base station maydetermine that a semi-static HARQ-ACK codebook corresponding to whichindicator value includes the PDSCH, by using time domain resourceassignment information occupied by the PDSCH candidates.

According to another aspect, the UE may determine that a semi-staticHARQ-ACK codebook corresponding to which indicator value includesHARQ-ACK associated with the PDSCH, according to k1 values(PDSCH-to-HARQ feedback timing indicators) indicated by the PDCCH (orDCI). Here, the k1 value is indicated via a PDSCH-to-HARQ_feedbacktiming indicator field of the PDCCH (or DCI), and corresponds to aninterval (=number of slots) between a slot in which a scheduled PDSCHends and a slot in which the PUCCH associated with HARQ-ACK istransmitted. For example, when 8 k1 values are configured or given tothe UE, HARQ-ACK of PDSCHs indicated by four small k1 values among the 8k1 values may be included in the semi-static HARQ-ACK codebookcorresponding to the indicator value of 0, and HARQ-ACK of PDSCHsindicated by the remaining four large k1 values may be included in thesemi-static HARQ-ACK codebook corresponding to the indicator value of 1.

According to another aspect, the UE may determine that a semi-staticHARQ-ACK codebook corresponding to which indicator value includesHARQ-ACK of the PDSCH, according to length (number of occupied symbols)values of the PDSCH indicated by the PDCCH (or DCI). For example, if the(symbol) length of a PDSCH is 2 or 4, HARQ-ACK associated with the PDSCHis included in the semi-static HARQ-ACK codebook corresponding to theindicator value of 0, and HARQ-ACK associated with a

PDSCH with the (symbol) length of 7 or more may be included in thesemi-static HARQ-ACK codebook corresponding to the indicator value of 1.

According to another aspect, the UE may determine that a semi-staticHARQ-ACK codebook corresponding to which indicator value includesHARQ-ACK of the PDSCH, according to a PDSCH mapping type indicated bythe PDCCH (or DCI). For example, if the PDSCH mapping type indicates A,HARQ-ACK of the PDSCH is included in the semi-static HARQ-ACK codebookcorresponding to the indicator value of 0, and if the PDSCH mapping typeindicates B, HARQ-ACK of the PDSCH may be included in the semi-staticHARQ-ACK codebook corresponding to the indicator value of 1.

According to another aspect, the UE may determine that a semi-staticHARQ-ACK codebook corresponding to which indicator value includesHARQ-ACK associated with each PDSCH, according to an index of a timedomain resource assignment field indicated by the PDCCH (or DCI). Forexample, HARQ-ACK associated with PDSCHs indicated by the index 0 to 7(bits 0000 to 0111) may be included in the semi-static HARQ-ACK codebookcorresponding to the indicator value of 0, and HARQ-ACK associated withPDSCHs indicated by the remaining indices 8 to 15 (bits 1000 to 1111)may be included in the semi-static HARQ-ACK codebook corresponding tothe indicator value of 1.

According to another aspect, when the base station configures, for theUE, a semi-static HARQ-ACK codebook of a specific indicator value, thenumber of pieces of HARQ-ACK (or PDSCHs) required per slot may beconfigured. For example, if two HARQ-ACK bits are configured per slot,when the UE generates a semi-static HARQ-ACK codebook of a specificindicator value, a semi-static HARQ-ACK codebook including up to 2 bitsper slot may be generated. In other words, the UE expects to receive upto two PDSCHs (1 bit per PDSCH) indicated by the specific indicatorvalue in one slot. The numbers of pieces of HARQ-ACK (or PDSCHs)required per slot may be configured to be different values insemi-static HARQ-ACK codebooks corresponding to different indicatorvalues.

According to another aspect, the UE may configure an HARQ-ACK codebookof a specific indicator value in a semi-static HARQ-ACK codebook manner,and may configure an HARQ-ACK codebook of another specific indicatorvalue in a dynamic HARQ-ACK codebook manner.

According to another aspect, when the UE receives only one PDSCH havinga specific indicator value (that is, if there is no HARQ-ACK of anotherPDSCH to be multiplexed), the UE may transmit only HARQ-ACK for the onereceived PDSCH via the PUCCH.

According to another aspect, when the UE receives configurationinformation of a PUCCH resource indicator (PRI) from the base station,the UE may receive configuration information of an indicatorcorresponding to each PRI value. For example, it is assumed that anindicator may have four values, such as 0, 1, 2, and 3, and the UEreceives 16 PUCCH configuration and PRI values (=0, 1, . . . , 15) fromthe base station. In this case, when each PUCCH configuration and PRIvalue is configured, the base station may configure 0, 1, 2, or 3 as anindicator value for the UE. That is, the indicator value of 0 may beconfigured for a PRI value of 0, 1, 2, or 3, the indicator value of 1may be configured for a PRI value of 4, 5, 6, or 7, an indicator valueof 2 may be configured for a PRI value of 8, 9, 10, or 11, and anindicator value of 3 may be configured for a PRI value of 12, 13, 14, or16. The UE may find out an indicator value on the basis of a PRI valueof DCI for scheduling of PDSCH. In the previous example, if the PRIvalue of DCI is 10, the UE may know that the indicator value is 2.

Generation and transmission of the first and second HARQ-ACK codebooksby the UE according to S1210 correspond to operation of the processor110 of FIG. 11.

The UE determines whether there is a collision when multiple PUCCHs aretransmitted, in S1215. PRIs are allocated to the first PUCCH and thesecond PUCCH, to which the first HARQ-ACK codebook and the secondHARQ-ACK codebook are mapped respectively, according to a specific rule.

For example, referring to FIG. 13, PUCCH resources for transmittingHARQ-ACK of two PDSCHs having the indicator value of 0 may be determinedaccording to a

PRI indicated in the PDCCH (or DCI) scheduled later from among the twoPDSCHs. Similarly, PUCCH resources for transmitting HARQ-ACK of twoPDSCHs having the indicator value of 1 may be determined according to aPRI indicated in the PDCCH (or DCI) scheduled later from among the twoPDSCHs.

If the PUCCH resources indicated by two PRI values do not overlap eachother, the UE may determine that the two PUCCHs do not collide in oneslot. On the other hand, if the resources of PUCCHs 1420 and 1430corresponding to two PRI values (or different indicator values) overlapeach other in a following slot 1410 as shown in FIG. 14, it isdetermined that the two PUCCH transmissions collide.

Therefore, the UE transmits at least one PUCCH of the first PUCCH andthe second PUCCH to the base station in the same slot on the basis of anindicator corresponding to each PUCCH, in S1220.

That is, if a collision occurs in S1215, both PUCCHs cannot betransmitted. That is, when the UE transmits two PUCCHs in one slot, ifthe resource of the PUCCH corresponding to the indicator value of 0 andthe resource of the PUCCH resource corresponding to the indicator valueof 1 overlap, the UE cannot transmit the two PUCCHs at the same time.Here, the overlapping resources may be time and/or frequency resources.

In this case, there may be a method in which the UE drops one PUCCHamong the first PUCCH corresponding to the indicator value of 0 and thesecond PUCCH corresponding to the indicator value of 1 and transmits theother PUCCH, or a method in which the HARQ-ACK codebooks of the firstPUCCH corresponding to the indicator value of 0 and the second PUCCHcorresponding to the indicator value of 1 are multiplexed andtransmitted via one PUCCH. The term “drop” may be replaced with termssuch as suspend, discard, and postpone. Hereinafter, such operationswill be described in a more specific embodiment.

As an example, the UE may select or determine a PUCCH for transmissionfrom among two PUCCHs on the basis of an indicator value. Specifically,a method of determining whether to drop one of two PUCCHs and transmitthe other PUCCH is as follows.

In one aspect, the UE transmits a PUCCH corresponding to the firstindicator value (e.g., 0) and drops a PUCCH corresponding to the secondindicator value (e.g., 1). Here, a case in which the indicator value is0 may be considered to have higher priority than a case in which theindicator value is 1. Which of the indicator values of 0 and 1 has ahigher priority may be determined differently. Here, the priority of aPUCCH may be determined differently according to a type of service dataor a type of traffic carried by a PDSCH associated with each PUCCH. Forexample, when a PDSCH associated with the first PUCCH carriesURLLC-related data and a PDSCH associated with the second PUCCH carrieseMBB-related data, the first PUCCH may have a higher priority than thesecond PUCCH.

In another aspect, the UE transmits a PUCCH corresponding to anindicator value based on the most recently received PDCCH (or DCI), anddrops a PUCCH corresponding to an indicator value of otherwise.

In another aspect, a PUCCH having a lower (i.e., more reliable) value ofa code rate from among the two colliding or overlapping PUCCHs istransmitted, and the other PUCCH is dropped.

In another aspect, a PUCCH of a preceding resource from among the twocolliding or overlapping PUCCHs is transmitted, and a PUCCH of afollowing resource is dropped. Determination of a preceding resource maybe based on last symbols of resources, wherein it may be said that, ifthe last symbols are the same, a resource with a preceding start symbolis a preceding resource.

In another aspect, a PUCCH occupying a longer symbol from among the twocolliding or overlapping PUCCHs is transmitted and a PUCCH occupying asmaller symbol is dropped. That is, a transmitted PUCCH and a PUCCH tobe dropped may be determined on the basis of the length (the number ofsymbols) occupied by the PUCCH.

In another aspect, a PUCCH with a small PRI value from among the twocolliding or overlapping PUCCHs is transmitted, and a PUCCH with a largePRI value is dropped. That is, a transmitted PUCCH and a PUCCH to bedropped may be determined on the basis of the PRI value of the PUCCH.

As another example, the UE may multiplex HARQ-ACK codebooks of twoPUCCHs, and then may transmit the same via one PUCCH. In order totransmit, via one PUCCH, two HARQ-ACK codebooks to be originally mappedto two PUCCHs, the UE may process or transform the HARQ-ACK codebooksaccording to the following embodiment.

In one aspect, the UE may generate one merged large HARQ-ACK codebook bysuccessively connecting HARQ-ACK codebooks according to a sequence ofindicator values, and may transmit the HARQ-ACK codebook via one PUCCH.

In another aspect, the UE may newly generate an HARQ-ACK codebook forPDSCH candidates associated with two colliding or overlapping PUCCHs(that is, generating a semi-static HARQ-ACK codebook for all PDSCHcandidates), and may transmit the HARQ-ACK codebook via one PUCCH.Alternatively, when the UE generates one merged large HARQ-ACK codebookby continuously connecting HARQ-ACK codebooks according to the sequenceof indicator values, HARQ-ACK bits included in a preceding HARQ-ACKcodebook may be excluded from a following HARQ-ACK codebook. Theadvantage of this example is that when HARQ-ACK bits for one PDSCHcandidate exist in both overlapping two PUCCHs, there is no need forduplicate transmissions.

Determination, according to S1215, of whether there is a collision whenthe UE transmits multiple PUCCHs corresponds to the operation of theprocessor 110 of FIG. 11.

In addition, transmission of at least one PUCCH among the first PUCCHand the second PUCCH in the same slot by the UE on the basis of anindicator corresponding to each PUCCH according to S1220 may correspondto the operation of the communication module 120 of FIG. 11. Receptionof at least one PUCCH among the first PUCCH and the second PUCCH in thesame slot from the UE by the base station on the basis of an indicatorcorresponding to each PUCCH according to S1220 may correspond to theoperation of the communication module 220 of FIG. 11.

Timing Design (Finer k1 Granularity) of PDSCH and HARQ-ACK When MultiplePUCCHs are Transmitted in One Slot

In order to indicate, to the UE, a slot for transmission of HARQ-ACKassociated with a PDSCH, the base station may include a k1 value(PDSCH-to-HARQ feedback timing indicator) in a PDCCH (or DCI) forscheduling of the PDSCH so as to transmit the k1 value to the UE. The k1value is indicated via a PDSCH-to-HARQ feedback timing indicator fieldof the PDCCH (or DCI), and corresponds to an interval (=number of slots)between a slot in which the scheduled PDSCH ends and a slot in which thePUCCH associated with HARQ-ACK is transmitted. However, if a unit of thek1 value is a slot, there exists ambiguity in defining timing fortransmission of two or more pieces of HARQ-ACK (or PUCCHs) in one slot.

Therefore, in this embodiment, in order to transmit multiple PUCCHsassociated with multiple pieces of HARQ-ACK in one slot, the unit (orgranularity) of the k1 value is defined to be a sub-slot, that is asmaller unit compared to a basic slot. For example, as shown in FIG. 15,the unit of k1 may be determined to be a half slot of the basic slot. Inthis case, one basic slot includes two half slots (k−1 and k).Therefore, the k1 value is defined to be the number of half slotsincluded between half slot k in which the scheduled PDSCH ends and halfslot n in which the PUCCH for transmission of HARQ-ACK is transmitted.

In this case, an interval between reception timing of the PDSCH andtransmission timing of an HARQ-ACK codebook associated with the PDSCHmay be defined in units of the number (=b) of symbols less than thenumber (=a) of symbols constituting one slot.

As an example, when the unit of the k1 value is given as a sub-slot (ora set of symbols), the k1 value indicates the number of sub-slotsbetween a sub-slot including a last symbol of the PDSCH and a sub-slotincluding a first symbol of the PUCCH. For example, if the value of k1is 0, this indicates that the sub-slot including the last symbol of thePDSCH and the sub-slot including the first symbol of the PUCCH are thesame.

As another example, when the unit of the k1 value is given as a sub-slot(or a set of symbols), the k1 value indicates the number of sub-slotsbetween the sub-slot including the last symbol of the PDSCH and thesub-slot including the first symbol of the PUCCH. For example, if the k1value is 0, this indicates that a last sub-slot of the slot includingthe last symbol of the PDSCH and the sub-slot including the first symbolof the PUCCH are the same.

As another example, when the unit of the k1 value is given as a sub-slot(or a set of symbols), the k1 value indicates the number of sub-slotsbetween the most preceding sub-slot among sub-slots after T_(proc, 1)time from the last symbol of the PDSCH and the sub-slot including thefirst symbol of the PUCCH. T_(proc, 1) represents a minimum time ittakes for the UE to receive the PDSCH and to transmit valid HARQ-ACK.3GPP TS38.214 document may be referred to for a value of T_(proc, 1).

As described above, when the unit of the k1 value is given as a sub-slot(or a set of symbols), if a situation in which multiple PUCCHs overlapwithin one slot occurs, the operation of the UE will be described asfollows. This is for a method of PUCCH transmission in a situation wherePUCCH resources indicated in units of half slots (or k1 unit) overlap.

FIG. 16 is a diagram illustrating a situation in which multiple PUCCHtransmissions collide within one slot according to an example.

Referring to FIG. 16, when a PUCCH (indexed with indicator value=0) 1620starting from a preceding half slot and a PUCCH (indexed with indicatorvalue=1) 1630 starting from a following half slot overlap, the UE cannottransmit both PUCCHs at the same time. Here, the UE may drop one PUCCHamong the two PUCCHs and transmit the other PUCCH, or may transmitHARQ-ACK codebooks of the two PUCCHs via one PUCCH.

As an example, the UE may determine a PUCCH for transmission from amongthe two PUCCHs on the basis of an indicator value. Specifically, amethod of determining whether to drop one of the two PUCCHs and transmitthe other PUCCH is as follows.

In one aspect, the UE transmits a PUCCH corresponding to the firstindicator value (e.g., 0) and drops a PUCCH corresponding to the secondindicator value (e.g., 1). Here, a case in which the indicator value is0 may be considered to have higher priority than a case in which theindicator value is 1. Which of the indicator values of 0 and 1 has ahigher priority may be determined differently.

In another aspect, the UE transmits a PUCCH corresponding to anindicator value based on the most recently received PDCCH (or DCI), anddrops a PUCCH corresponding to an indicator value of otherwise.

In another aspect, a PUCCH having a lower (i.e., more reliable) value ofa code rate from among the two colliding or overlapping PUCCHs istransmitted, and the other PUCCH is dropped.

In another aspect, a PUCCH of a preceding resource from among the twocolliding or overlapping PUCCHs is transmitted, and a PUCCH of a laterresource is dropped. Determination on preceding of a resource may bebased on last symbols of resources, wherein it may be said that, if thelast symbols are the same, a resource with a preceding start symbol is apreceding resource.

In another aspect, a PUCCH occupying a longer symbol from among the twocolliding or overlapping PUCCHs is transmitted and a PUCCH occupying asmaller symbol is dropped. That is, a transmitted PUCCH and a PUCCH tobe dropped may be determined on the basis of the length (the number ofsymbols) occupied by the PUCCH.

In another aspect, a PUCCH with a small PRI value from among the twocolliding or overlapping PUCCHs is transmitted, and a PUCCH with a largePRI value is dropped. That is, a transmitted PUCCH and a PUCCH to bedropped may be determined on the basis of the PRI value of the PUCCH.

As another example, the UE may multiplex HARQ-ACK codebooks of twoPUCCHs, and then may transmit the same via one PUCCH. In order totransmit, via one PUCCH, two

HARQ-ACK codebooks to be originally mapped to two PUCCHs, the UE mayprocess or transform the HARQ-ACK codebooks according to the followingembodiment.

In one aspect, the UE may generate one merged large HARQ-ACK codebook bysuccessively connecting HARQ-ACK codebooks in a time sequence, and maymap the HARQ-ACK codebook to one PUCCH and transmit the same. Forexample, the UE may perform configuration so that an HARQ-ACK codebook,for which transmission in a preceding half slot in one slot isindicated, is located in front of an HARQ-ACK codebook for whichtransmission in a following half slot is indicated.

In another aspect, the UE may newly generate an HARQ-ACK codebook forPDSCH candidates associated with two colliding or overlapping PUCCHs(that is, generating a semi-static HARQ-ACK codebook for all PDSCHcandidates), and may transmit the HARQ-ACK codebook via one PUCCH.Alternatively, when the UE generates one merged large HARQ-ACK codebookby continuously connecting HARQ-ACK codebooks according to a sequence ofindicator values, HARQ-ACK bits included in a preceding HARQ-ACKcodebook may be excluded from a following HARQ-ACK codebook. Theadvantage of this example is that when HARQ-ACK bits for one PDSCHcandidate exist in both overlapping two PUCCHs, there is no need forduplicate transmissions.

These operations at HARQ-ACK collision according to FIG. 16 may beperformed by the processor 110 or the communication module 120 of FIG.11.

Method of Configuring Ssub-Slot and Method of Generating Ssemi-SstaticHARQ-ACK Codebook

The present embodiment relates to a method of dividing a slot intomultiple sub-slots.

For example, when a slot including 14 symbols is divided into twosub-slots, each sub-slot may include 7 consecutive symbols. In thiscase, a first sub-slot includes first 7 symbols of the slot, and asecond sub-slot includes last 7 symbols of the slot. Alternatively, whenthe slot including 14 symbols is divided into two sub-slots, the firstsub-slot may include odd-numbered symbols of the slot, and the secondsub-slot may include even-numbered symbols of the slot.

As an example, according to a first method of dividing a slot includingK symbols into N sub-slots, (K mod N) sub-slots may include floor(K/N)+1consecutive symbols, and N−(K mod N) sub-slots may include floor(K/N)consecutive symbols.

In one aspect, among n sub-slots, (K mod N) sub-slots having one moresymbols may be located at a front end of each slot, and the remainingN−(K mod N) sub-slots having one fewer symbol may be located at a rearend of each slot.

In another aspect, among n sub-slots, N-(K mod N) sub-slots having onefewer symbol may be located at the front end of the slot, and theremaining (K mod N) sub-slots having one more symbols may be located atthe rear end of the slot.

In another aspect, among n sub-slots, (K mod N) sub-slots having onemore symbols and N-(K mod N) sub-slots having one fewer symbol may belocated at the front end and the rear end of each slot while alternatingwith each other.

As another example, according to a second method of dividing a slotincluding K symbols into N sub-slots, an n-th sub-slot may includefloor(K/N)*i+nth (i=0, 1, . . . ) symbols.

As another example, the UE may divide each slot into multiple sub-slotson the basis of configured time domain resource assignment informationof a PDSCH. For example, the slot may be divided into sub-slotsaccording to a sequence of locations of last symbols of the PDSCH in thetime domain resource allocation information of the PDSCH. Up to a lastsymbol of last symbols of A PDSCHs that are most preceding in thesequence of the last symbols of the PDSCHs may be divided into a firstsub-slot. Subsequently, the remaining sub-slots may be divided using theabove method.

As another example, the UE may divide each slot into multiple sub-slotson the basis of configured information on symbols occupied by a PUCCH.For example, each slot may be divided into sub-slots according to asequence of locations of last symbols of the PUCCH in the information ofthe symbols occupied by the PUCCH. Up to a last symbol of last symbolsof A PUCCHs that are most preceding in the sequence may be divided intoa first sub-slot. Subsequently, the remaining may be divided using theabove method.

The present embodiment also discloses a method of generating asemi-static HARQ-ACK codebook when the unit of the k1 value isconfigured in units of sub-slots (or a set of symbols). The method ofgenerating the semi-static HARQ-ACK codebook according to the presentembodiment may correspond to the operation of the processor 110 or thecommunication module 120 of FIG. 11.

FIG. 17 is a diagram exemplarily illustrating multiple PDSCH candidatestransmittable over sub-slots according to an example.

Referring to FIG. 17, it is assumed that three PDSCH candidates exist inone slot. A first sub-slot (sub-slot 0) includes PDSCH candidate # 1.When the last symbol of a PDSCH candidate is included in a specificsub-slot, it may be considered that the PDSCH candidate is included inthe specific sub-slot. A second sub-slot (sub-slot 1) includes PDSCHcandidate # 2 and PDSCH candidate # 3. PDSCH candidate # 1 and PDSCHcandidate # 2 overlap over the same symbols in the first sub-slot(sub-slot 0), whereas PDSCH candidate # 3 does not overlap with otherPDSCH candidates.

If the UE is able to receive only one PDSCH in one symbol, combinationsof PDSCH candidates receivable by the UE in the slot in FIG. 17 are{PDSCH candidate # 1}, {PDSCH candidate # 2}, {PDSCH candidate # 3},{PDSCH candidate # 1, PDSCH candidate # 3}, and {PDSCH candidate # 2,PDSCH candidate # 3}. That is, in the slot shown in FIG. 17, the maximumnumber of PDSCH candidates concurrently receivable by the UE is two.Here, if it is assumed that 1-bit HARQ-ACK is generated and transmittedfor one PDSCH candidate, it may be seen in the present embodiment thatthe number of HARQ-ACK bits that the UE needs to include in asemi-static HARQ-ACK codebook, for receivable PDSCH candidates in theslot, is two.

However, if the unit of the k1 value is given as a half slot, the UEgenerates a semi-static HARQ-ACK codebook for each half slot. An exampleof generating a semi-static HARQ-ACK codebook based on a half slot isshown in FIG. 18.

Referring to FIG. 18, a PDSCH combination receivable in a first halfslot (sub-slot 0) is {PDSCH candidate # 1}, and therefore the number ofthe PDSCH combinations receivable in the first half slot (sub-slot 0) isup to one. Therefore, the UE needs to include 1-bit HARQ-ACK 1810 in thesemi-static HARQ-ACK codebook for the first half slot. Subsequently,PDSCH combinations receivable in a second half slot (sub-slot 1) are{PDSCH candidate # 2}, {PDSCH candidate # 3}, and {PDSCH candidate # 2,PDSCH candidate # 3}, and therefore the number of the PDSCH combinationsreceivable in the second half slot (sub-slot 1) is up to two. Therefore,the UE needs to include 2-bit HARQ-ACK 1820 in the semi-static HARQ-ACKcodebook, for the second half slot (sub-slot 1). As a result, asituation arises in which the UE includes, for one slot, a total of 3bits 1810 and 1820 of HARQ-ACK in the semi-static HARQ-ACK codebook.

However, as described above, up to two PDSCHs are transmittable in oneslot, and therefore it may be seen that an unnecessary 1-bit overheadoccurs when compared to a situation in which 2-bit HARQ-ACK is includedin the semi-static HARQ-ACK codebook. Therefore, there is a need for amethod for reducing such overhead.

According to the present embodiment, an HARQ-ACK codebook associatedwith a PDSCH may be configured to include the same number of pieces ofHARQ-ACK as the maximum number of PDSCHs receivable in one slot. Thatis, the UE may generate an HARQ-ACK codebook including the same numberof pieces of HARQ-ACK as the maximum number of PDSCHs receivable in oneslot.

As an example, when the unit of the k1 value is a sub-slot (or a set ofsymbols) unit, the UE bundles all sub-slots included in one slot andgenerates a semi-static HARQ-ACK codebook by using PDSCH candidatesincluded in the sub-slots. That is, the UE may generate a semi-staticHARQ-ACK codebook to be transmitted in sub-slot n as shown in FIG. 19.The operation of FIG. 19 may correspond to the operation of theprocessor 110 or the communication module 120 of FIG. 11.

FIG. 19 illustrates generation of a semi-static HARQ-ACK codebook basedon a half slot according to another example.

Referring to FIG. 19, the UE takes out a largest k1 value (=k1_max) fromk1_set that is a set of k1 values which can be indicated by the basestation. When it is assumed that an index of a slot including a sub-slotcorresponding to n−(k1_max) is X, and N subslot sub-slots are includedin one slot, X is floor((n−k1_max)/N subslot).

The UE takes out, from k1_set, k1 values indicating sub-slots includedin slot X. That is, when an element of the k1 set is k1_value, the UEtakes out all k1_value that satisfy X =floor((n−k1 value)/N subslot). Aset of k1 values (including k1_max) taken out in the above procedure isreferred to as k1_max set. Taking out k1 values from k1_set therebyconfiguring k1_max set, as described above, is referred to as S1900.

It is assumed that a set of PDSCH candidates receivable in one slot isR. If a last symbol of a PDSCH candidate included in set R is includedin one of sub-slots included in k1_max set, the UE leaves, as it is, thePDSCH candidate in set R, otherwise, the UE excludes the PDSCH candidatefrom set R. In addition, when a symbol of the PDSCH candidate includedin set R overlaps with a symbol configured for uplink in a semi-staticUL/DL configuration, the UE excludes the PDSCH candidate from set R.Excluding the PDSCH candidate from set R according to predeterminedcriteria is referred to as S1905.

The UE performs the following A and B for the PDSCH candidates includedin set R.

A. The UE allocates new 1 bit to a PDSCH candidate having a mostpreceding last symbol. If there is a PDSCH candidate overlapping thePDSCH candidate by even one symbol in set R, the UE allocates, to theoverlapping PDSCH candidate, the same bit position as that of the PDSCHcandidate having the most preceding last symbol. The UE excludes thePDSCH candidates (including the PDSCH candidate having the mostpreceding last symbol) from set R. Performing A is referred to as S1910.

B. The UE repeats A until set R becomes an empty set, in S1915.

The UE repeats S1900, S1905, and S1910 until k1 set becomes an emptyset. As a result, the UE may allocate one HARQ-ACK (index 1) to PDSCHcandidate # 1 or PDSCH candidate # 2 as shown in FIG. 20, and mayallocate another HARQ-ACK (index 2) to PDSCH candidate # 3.

Each of these operations according to FIG. 19 may be performed by theprocessor 110 of FIG. 11.

HARQ-ACK Multiplexing Indicator

According to the present embodiment, methods of configuring,transmitting, and receiving an HARQ-ACK multiplexing indicator areprovided. The method of configuring an HARQ-ACK multiplexing indicatormay be performed by the processor 110 of FIG. 11, the method ofgenerating and transmitting an HARQ-ACK multiplexing indicator may beperformed by the communication module 120 of FIG. 11, and the method ofreceiving an HARQ-ACK multiplexing indicator may be performed by thecommunication module 220 of FIG. 11, wherein the methods are disclosedthroughout the present specification.

The UE may receive information on whether HARQ-ACK of the PDSCH shouldbe multiplexed with other HARQ-ACK in the PDCCH (or DCI) for schedulingof the PDSCH. In the present specification, the information is referredto as an HARQ-ACK multiplexing indicator. The HARQ-ACK multiplexingindicator may be determined to 1 bit. When the HARQ-ACK multiplexingindicator is 1 bit, if the HARQ-ACK multiplexing indicator is 0, thismay indicate that HARQ-ACK of the PDSCH is multiplexed with HARQ-ACK ofanother PDSCH and is not transmitted, and if the HARQ-ACK multiplexingindicator is 1, this may indicate that HARQ-ACK of the PDSCH ismultiplexed with HARQ-ACK of another PDSCH and is transmitted.

Here, not multiplexing specific HARQ-ACK with HARQ-ACK of another PDSCHindicates that there is no HARQ-ACK information of another PDSCH in aPUCCH that is transmitted including the specific HARQ-ACK. Therefore,the PUCCH in which no HARQ-ACK has been multiplexed includes HARQ-ACK of1 bit (or 2 bits when two transmission blocks are configured to betransmitted on the PDSCH), and the HARQ-ACK may be transmitted in one ofPUCCH format 0 or PUCCH format 1 according to a bit size. On the otherhand, multiplexing and transmitting specific HARQ-ACK with HARQ-ACK ofanother PDSCH indicates that HARQ-ACK information of another PDSCH maybe included in the PUCCH that is transmitted including the specificHARQ-ACK.

When specific HARQ-ACK is multiplexed with HARQ-ACK of another PDSCH andtransmitted, the UE generates an HARQ-ACK codebook by using a dynamicHARQ-ACK codebook scheme or a semi-static HARQ-ACK codebook scheme, andmaps the generated HARQ-ACK codebook to the PUCCH so as to transmit thesame.

FIG. 21 illustrates PUCCH transmission by the UE according to anHARQ-ACK multiplexing indicator according to an example.

Referring to FIG. 21, the UE receives a total of four PDSCHs 2101, 2102,2103, and 2104 in a preceding slot 2100. Each PDSCH corresponds to anHARQ-ACK multiplexing indicator of a specific value. For example, thefirst PDSCH 2101 and the second PDSCH 2102 may correspond to an HARQ-ACKmultiplexing indicator value of 1, and the third PDSCH 2103 and thefourth PDSCH 2104 may correspond to an HARQ-ACK multiplexing indicatorvalue of 0.

HARQ-ACK information of two PDSCHs 2101 and 2102 having the HARQ-ACKmultiplexing indicator value of 1 is transmitted via one PUCCH 2111.HARQ-ACK of two PDSCHs 2103 and 2104 having the HARQ-ACK multiplexingindicator value of 0 are transmitted via different PUCCH resources 2112and 2113, respectively.

Here, PUCCH resources associated with the PDSCHs 2103 and 2104 havingthe HARQ-ACK multiplexing indicator value of 0 are indicated via PRIvalues for scheduling of the PDSCHs 2103 and 2104. If PUCCHs whichtransmit HARQ-ACK of different PDSCHs having the HARQ-ACK multiplexingindicator value of 0 (multiplexing with HARQ-ACK of another PDSCH is notpossible) overlap in the same symbol, concurrent transmission isimpossible. In this case, a method of processing the PUCCHs is asfollows.

As an example, the UE may multiplex HARQ-ACK information of PUCCHs intoone PUCCH and transmit the same.

As another example, the UE transmits the PUCCH of the PDSCH byprioritizing HARQ-ACK of the PDSCH (that is, when the PDCCH forscheduling the PDSCH starts late or ends late) scheduled later, anddrops overlapping the other PUCCH without transmission.

As another example, the UE may not expect the two PUCCHs to overlap inone symbol.

As another example, even if 0 (multiplexing with HARQ-ACK of anotherPDSCH is impossible) has been indicated as the HARQ-ACK multiplexingindicator value, the UE may be configured so that HARQ-ACK multiplexingis partially possible. For example, when two PDSCHs 2103 and 2104, inwhich 0 has been indicated as the HARQ-ACK multiplexing indicator value,are indicated to be transmitted in the same PUCCH resource (or if thetwo PDSCHs have the same PRI value, or overlap in at least one symbol),HARQ-ACK of the two PDSCHs 2103 and 2104 are multiplexed andtransmitted. In this case, the HARQ-ACK bit of the PDSCH scheduled lateris located subsequent to the HARQ-ACK bit of the PDSCH scheduledearlier. This is shown in FIG. 22.

FIG. 22 illustrates PUCCH transmission by the UE according to anHARQ-ACK multiplexing indicator according to another example.

First, referring to (a) in FIG. 22, even if the HARQ-ACK multiplexingindicator values associated with the third and fourth PDSCHs 2103 and2104 are indicated to be 0 in the preceding slot 2200 (i.e., disable ofmultiplexing), if the PRI values of the third and fourth PDSCHs 2103 and2104 are equal to i, the UE may transmit HARQ-ACK of the two PDSCHs in aPUCCH resource corresponding to PRI=i.

Referring to (b) in FIG. 22, when the HARQ-ACK multiplexing indicatorvalues associated with the third and fourth PDSCHs 2103 and 2104 areindicated to be 0 in the preceding slot 2200, if the PRI values of thethird and fourth PDSCHs 2103 and 2104 are not the same (i and j), the UEmay transmit each piece of HARQ-ACK information in a PUCCH resourcecorresponding to each PRI value.

The PUCCH resources for transmitting HARQ-ACK of PDSCHs having theHARQ-ACK multiplexing indicator value of 1 and the PUCCH resourcestransmitting HARQ-ACK of the PDSCHs having the HARQ-ACK multiplexingindicator value of 0 may overlap. In this case, the UE may transmitPUCCH in the following way.

As an example, the UE always preferentially transmits a PUCCH fortransmitting HARQ-ACK of PDSCHs having the HARQ-ACK multiplexingindicator value of 0 and may drop a PUCCH for transmitting HARQ-ACK ofthe PDSCHs having the HARQ-ACK multiplexing indicator value of 1.

As another example, if the last symbol of the PUCCH for transmittingHARQ-ACK of the PDSCHs having the HARQ-ACK multiplexing indicator valueof 1 ends before or ends at the same time as the last symbol of thePUCCH for transmitting HARQ-ACK of PDSCHs having the HARQ-ACKmultiplexing indicator value of 0, the UE may attach an HARQ-ACK bit ofthe PDSCH having the HARQ-ACK multiplexing indicator value of 0 to anHARQ-ACK bit of the PDSCHs having the HARQ-ACK multiplexing indicatorvalue of 1, and may transmit the same in the PUCCH resource of thePDSCHs having the HARQ-ACK multiplexing indicator value of 1.

In the present specification, the HARQ-ACK multiplexing indicator isexpressed to be 1 bit for convenience and has been described as beingexplicitly transmitted. However, the HARQ-ACK multiplexing indicator maybe implicitly indicated as follows.

As an example, the UE may determine an HARQ-ACK multiplexing indicatoron the basis of an RNTI scrambled to PDCCH. For example, if a PDCCH (orDCI) for scheduling of a PDSCH is scrambled with C-RNTI, the UE maydetermine that an HARQ-ACK multiplexing indicator of the PDSCH has avalue of 1 (that is, being able to be multiplexed with HARQ-ACKinformation of another PDSCH). On the other hand, if the PDCCH (or DCI)for scheduling of the PDSCH is scrambled with an RNTI (e.g., RNTI for aURLLC service) other than a C-RNTI, the UE may determine that theHARQ-ACK multiplexing indicator of the PDSCH has a value of 0 (that is,being unable to be multiplexed with HARQ-ACK of another PDSCH).

As an example, the UE may determine an HARQ-ACK multiplexing indicatoron the basis of a k1 value included in the PDCCH (or DCI). Here, the k1value indicates a time interval between a scheduled PDSCH and HARQ-ACKof the PDSCH or timing of the PDSCH and the HARQ-ACK. Therefore, for aPDSCH for a URLLC service, it is generally necessary to quickly indicateor transmit HARQ-ACK. Therefore, if the k1 value is smaller than apredetermined specific k1 value, the UE may determine that the HARQ-ACKmultiplexing indicator is 0. On the other hand, if the k1 value islarger than or equal to the predetermined specific k1 value, the UE maydetermine that the HARQ-ACK multiplexing indicator is 1. Here, thepredetermined specific k1 value may be determined in units of slots(e.g., 1 slot or 2 slots), may be determined in units of sub-slots, ormay be determined in units of absolute times (e.g., 0.5 ms or 0.25 ms).Alternatively, when a specific k1′ value is indicated from amongmultiple k1 values, the UE may determine an HARQ-ACK multiplexingindicator value to be 0. That is, when the UE receives an indication ofthe k1′ value, the UE transmits only HARQ-ACK for one PDSCH withoutmultiplexing of an HARQ-ACK codebook.

As another example, the UE may determine the HARQ-ACK multiplexingindicator on the basis of a modulation and coding scheme (MCS) value.Here, the MCS value indicates a code rate of a scheduled PDSCH. Ingeneral, high reliability is required for the PDSCH of a URLLC service.Therefore, if the code rate value is lower than a specific code ratevalue, the UE may determine that the HARQ-ACK multiplexing indicator is0. On the other hand, if the code rate value is larger than or equal tothe specific code rate value, the UE may determine that the HARQ-ACKmultiplexing indicator is 1. Alternatively, the UE may determine theHARQ-ACK multiplexing indicator on the basis of an MCS table used by thePDCCH (or DCI). When a specific PDCCH (or DCI) uses an MCS table thatprovides higher reliability (lower code rate), the UE may determine thatthe HARQ-ACK multiplexing indicator value of the PDCCH (or DCI) is 0.

As another example, the UE may determine that, as a combination ofspecific values indicated by other fields transmitted via DCI, theHARQ-ACK multiplexing indicator is 0 or 1.

As another example, the UE may determine the HARQ-ACK multiplexingindicator value on the basis of a search space (or CORESET) in which thePDCCH (or DCI) is detected. For example, the base station may separatelyinstruct a search space (or CORESET) for URLLC transmission to the UE.If the UE receives the PDCCH (or DCI) in the search space (or CORESET),the UE may determine that the HARQ-ACK multiplexing indicator value is0. On the other hand, if the UE receives the PDCCH (or DCI) in a searchspace (or CORESET) other than the search space (or CORESET), the UE maydetermine that the HARQ-ACK multiplexing indicator value is 1.Alternatively, the UE may distinguish the search space (or CORESET)without a separate explicit indication from the base station. Forexample, if a monitoring period of the search space (or CORESET) isshorter than a specific period, it may be determined that the searchspace (or CORESET) is a search space (or CORESET) for URLLCtransmission. The specific period may be, for example, one slot.

As another example, the UE may determine the HARQ-ACK multiplexingindicator value on the basis of a control channel element (CCE)aggregation level of a PDCCH received from the base station. Forexample, if the CCE aggregation level exceeds a specific value, the UEmay determine that the HARQ-ACK multiplexing indicator value of thePDCCH is 0. Here, the specific CCE aggregation level value may bedetermined to be 8 or 16. If the CCE aggregation level is smaller thanor equal to a specific value, the UE may determine that the HARQ-ACKmultiplexing indicator value of the PDCCH is 1.

As another example, the UE may determine the HARQ-ACK multiplexingindicator value on the basis of a DCI format (or length of DCI). Forexample, if compact DCI is configured for the UE, the UE may determinethat the HARQ-ACK multiplexing indicator value of the PDSCH scheduledvia the compact DCI is 0. On the other hand, if no compact DCI isconfigured for the UE, the UE may determine that the HARQ-ACKmultiplexing indicator value of PDSCH scheduled via corresponding DCIis 1. Here, the compact DCI is a DCI format for scheduling of URLLCPDSCH, and may be smaller than a payload size of fallback DCI (DCIformat 0_0/1_0).

As another example, the UE may determine the HARQ-ACK multiplexingindicator value on the basis of a PUCCH resource indicator (PRI) value.Here, a PRI included in PUCCH (or DCI) so as to be transmitted indicatesa PUCCH resource that is to be used by the UE from among PUCCH resourcesconfigured by the base station. If a predetermined specific value isindicated from among PRI values, the UE may determine that the HARQ-ACKmultiplexing indicator value is 0. This is because all the configuredPUCCH resources are not suitable for transmitting URLLC HARQ-ACK. Forexample, since a PUCCH resource for transmitting HARQ-ACK information of2 bits or less from among PUCCH resources is suitable for transmittingURLLC HARQ-ACK, if a PRI indicating the PUCCH resource is received, theUE may determine that the HARQ-ACK multiplexing indicator value is 0.Conversely, since a PUCCH resource exceeding 2-bit HARQ-ACK informationfrom among PUCCH resources is not suitable for transmitting the URLLCHARQ-ACK, if a PRI indicating the PUCCH resource is received, the UE maydetermine that the HARQ-ACK multiplexing indicator value is 1.

As another example, the UE may determine the HARQ-ACK multiplexingindicator value on the basis of an HARQ process number. For example,when a predetermined specific value is indicated for the UE from amongHARQ process numbers, the UE may determine that the HARQ-ACKmultiplexing indicator value is 0, and may transmit only HARQ-ACK forone PDSCH.

As another example, the UE may determine the HARQ-ACK multiplexingindicator value on the basis of a PDSCH group indicator value. The PDSCHgroup indicator is used to concurrently transmit multiple PUCCHs in oneslot. In this case, multiple HARQ-ACK bits may be multiplexed on thesame PUCCH resource. If the UE receives a specific value from amongPDSCH group indicators, the UE may determine that the HARQ-ACKmultiplexing indicator value is 0, and may transmit only HARQ-ACK forone PDSCH.

Method of Deriving k1 Value

The present embodiment discloses a method of deriving or interpreting ak1 value by the UE. The k1 value is an interval between a slot in whichthe scheduled PDSCH ends and a slot in which HARQ-ACK is transmitted, orthe number of slots (or the number of specific units (sub-slots) smallerthan slots). However, the UE actually needs a processing time until theUE receives and decodes a PDSCH, and generates a PUCCH for transmittingHARQ-ACK. Therefore, a specific k1 value, for example, k1=0, is a valuethat the UE cannot process realistically. Therefore, the k1 value of 0is a value that cannot be indicated to the UE. Accordingly, the presentembodiment discloses a method of defining a k1 value except for a valuethat cannot be indicated to the UE due to a processing time as describedabove.

As an example, the UE may determine the k1 value except for slotscompletely included between a last symbol of the PDSCH and a PDSCHprocessing time (T _(proc, 1)) Slots excluded from the above arereferred to as invalid slots. That is, the k1 value according to thepresent embodiment may be defined to be the number of valid slotsremaining after excluding invalid slots from among slots between a slotin which a scheduled PDSCH ends and a slot in which PUCCH fortransmission of HARQ-ACK is transmitted.

As another example, the UE may determine the kl value except for a slotconfigured as a semi-static DL symbol by a higher layer. For example,the UE excludes, when determining the k1 value, a slot including onlysemi-static DL symbols. Alternatively, the UE may exclude, whendetermining the k1 value, a slot in which all PUCCH transmissions areimpossible due to semi-static DL symbols.

The invalid slot may include slots in which a PUCCH resource indicatedby a PRI and the semi-static DL symbol overlap so that the PUCCH cannotbe transmitted. In this case, the k1 value may be defined to be thenumber of slots remaining after excluding invalid slots from among slotsbetween the slot in which the scheduled PDSCH ends and the slot in whichthe PUCCH for transmission of HARQ-ACK is transmitted.

This method of deriving or interpreting the kl value may be performed bythe processor 110 of FIG. 11.

Method of Determining PUCCH Resource When k1 or PRI Field is notIndicated to UE

In a PDCCH (or DCI) for scheduling of URLLC, a k1 or PRI field may notbe configured for the purpose of reducing DCI overhead (or payload sizeof DCI). Accordingly, the present embodiment discloses a method fordetermining a PUCCH resource when a k1 or PRI field is not configured inDCI.

As an example, when a k1 field (or PDSCH-to-HARQ feedback timingindicator field) for the UE is not configured (or indicated), a slotincluding a PUCCH resource of the UE may be determined to be a slot inwhich subsequent (indicated by PRI) PUCCH transmission is possible,except for slots completely included between a last symbol of the PDSCHand a PDSCH processing time (T _(proc, 1)).

As another example, when the k1 field for the UE is not configured (orindicated), the slot including the PUCCH resource of the UE may bedetermined to be a slot that does not overlap with a symbol indicated bya PRI and a semi-static DL symbol.

As another example, when no PRI field for the UE is configured (orindicated), the PUCCH resource of the UE may be determined to be a PUCCHresource that ends earliest from among PUCCH resources configured in theslot indicated by k1.

As another example, when no PRI field for the UE is configured (orindicated), the PUCCH resource of the UE may be determined to be a PUCCHresource that ends earliest from among PUCCH resources except for aPUCCH that does not satisfy the PDSCH processing time (T _(proc, 1)) inthe slot indicated by k1. Here, a PUCCH resource overlapping thesemi-static DL symbol may be excluded.

FIG. 23 is a diagram describing a method of determining a PUCCH resourcewhen k1 and PRI fields are not included (or indicated) in the UEaccording to an example.

Referring to FIG. 23, a total of four PUCCH resources (# 1, # 2, # 3,and # 4) are configured in slot b for a PDSCH of slot a. Among them,PUCCH resource # 1 may be excluded from the PUCCH resources for the UEdue to failing to satisfy a processing time condition. In addition, aPUCCH resource that ends earliest from among PUCCH resources # 2, # 3,and # 4 is # 3, and therefore the UE may determine PUCCH resource # 3 asa PUCCH resource for transmission of HARQ-ACK associated with PDSCH.

The method of determining a PUCCH resource may be performed by theprocessor 110 of FIG. 11.

Method of Transmitting HARQ-ACK Associated with SPS PDSCH

A minimum period that a semi-persistent scheduled (SPS) PDSCH may havein a Release 15 NR system is 10 ms. In addition, an interval between aPUCCH transmission slot and a PDSCH transmission slot for HARQ-ACKtransmission can be up to 16 slots. According to this configuration, itis impossible to transmit HARQ-ACK of two or more SPS PDSCHs in onePUCCH transmission slot. However, in Release 16, for a downlink URLLCservice, SPS PDSCH transmission having a period shorter than 10 ms hasbeen enhanced. In this case, a situation in which the UE transmitsHARQ-ACK of two or more SPS PDSCHs in one PUCCH transmission slot mayoccur. Therefore, a method of transmitting, by the UE, HARQ-ACK bitsassociated with multiple SPS PDSCHs in one slot should be clearlydefined.

The present embodiment may include receiving an SPS PDSCH in a firstslot by the UE, and if HARQ-ACK associated with the SPS PDSCH cannot betransmitted in a second slot that is a slot after k1 slots from thefirst slot, delaying transmission timing of HARQ-ACK associated with theSPS PDSCH until a third slot.

This will be described in more detail as follows. DCI for activation ofthe SPS PDSCH may include one k1 value. Here, the k1 value is a valueindicated by an HARQ feedback timing indicator field from the PDSCH, andindicates an interval or a slot difference between a slot in which thePDSCH is transmitted and a slot in which the PUCCH is transmitted.

The UE is scheduled to transmit a PUCCH including HARQ-ACK in slot n+k1that is lagged behind by the k1 value from slot n in which the SPS PDSCHis transmitted. However, slot n+k1 lagged behind by the k1 value fromslot n in which the SPS PDSCH is transmitted may not always be a slot inwhich PUCCH transmission is possible. For example, in a TDD system, asituation in which slot n+k1 lagged behind by the k1 value from slot nin which the SPS PDSCH is transmitted overlaps with a DL symbol mayoccur. In this case, the UE cannot transmit HARQ-ACK associated with SPSPDSCH in slot n+k1.

FIG. 24 is a diagram describing a method of transmitting, by the UE,HARQ-ACK bits associated with multiple SPS PDSCHs in one slot accordingto an example.

Referring to FIG. 24, if first SPS PDSCH transmission is scheduled inslot n, and PUCCH transmission associated with a first SPS PDSCH isimpossible in slot n+kl, the UE postpones transmission timing ofHARQ-ACK associated with the first SPS PDSCH to slot n+P+k1. If PUCCHtransmission is possible in slot n+P+k1, the UE may transmit HARQ-ACK ofthe SPS PDSCH. However, if PUCCH transmission is impossible even in slotn+P+k1, the UE cannot transmit HARQ-ACK of the first SPS PDSCH. In thiscase, the UE postpones the transmission timing of HARQ-ACK for the firstSPS PDSCH to slot n+2P+k1 again. With this pattern, the UE maycontinuously postpone, by P, the transmission timing of HARQ-ACK for thefirst SPS PDSCH. Here, P may be determined to be, for example, the samevalue as a period of the SPS PDSCH.

As an example, if PUCCH transmission is possible in slot n+P+k1, the UEmay multiplex and transmit HARQ-ACK for SPS PDSCH which has not beentransmitted before and HARQ-ACK for an SPS PDSCH received in slot n+P.That is, the UE may transmit a PUCCH including HARQ-ACK in a nearestslot capable of transmitting a PUCCH including HARQ-ACK among slots fromslot n, to which the SPS PDSCH is allocated, to slots n+i*P+k1 (i=0,1, .. . ).

As another example, the base station may indicate multiple k1 values totransmit HARQ-ACK of the SPS PDSCH to the UE. When the UE receivesmultiple K1 values (e.g., both k1_1 and k1_2) from the base station, themethod of transmitting HARQ-ACK is as follows. When a slot in which theSPS PDSCH is received is slot n, if a PUCCH can be transmitted inn+k1_1, transmission is performed. If the PUCCH cannot be transmitted inn+k1_1, the PUCCH is transmitted in n+k1_2.

As another example, the base station may indicate multiple k1 values totransmit HARQ-ACK of the SPS PDSCH to the UE. A first k1 value among themultiple k1 values is applied to the first SPS PDSCH, and a second k1value is applied to a second SPS PDSCH. That is, if the number ofconfigured k1 values is T, an M-th k1 value may be applied to an(i*T+M)th SPS PDSCH.

According to the present embodiment, reception of the SPS PDSCH by theUE and postponing HARQ-ACK associated with the SPS PDSCH by i*P and thentransmitting the same may be performed by the communication module 120of FIG. 11, and transmission of SPS PDSCH by the base station andpostponing HARQ-ACK associated with the SPS PDSCH by i*P and thenreceiving the same may be performed by the communication module 220 ofFIG. 11.

Method of Configuring Payload of Reduced DCI

The present embodiment is a method of reducing a payload size of DCI. Ak1 or PRI field may be excluded to reduce DCI overhead, and other fieldsmay also be excluded in a similar manner. Alternatively, only some ofoptions indicated by a DCI field may be included.

Here, if only some of options that the DCI field can indicate (e.g., Noptions) are included, a bit size of the DCI field becomesceil(log2(N)). However, if N does not appear as a power of 2, 2^(X)−Ncode points of the corresponding DCI field cannot be used. Here, X is asmallest value among integers that satisfy a condition that 2^(X) islarger than or equal to N. Therefore, in order to more efficiently usethe remaining code points, a method of joint encoding different DCIfields may be used.

As an example, it is assumed that a j-th DCI field includes Y(j) options(a zeroth option, a first option, . . . , a Y(j)th option). Here, asequence of options is numbered from zeroth. That is, a most precedingoption is the zeroth option. When DCI is received from the base station,the UE may obtain an option number in the j-th DCI field by using thefollowing equation.

Field(j)=floor(X/Z(j)) mod Y(j)   [Equation 1]

Referring to Equation 1, X=Σ_(k=0) ^(DCI_length−1)2^(b) ^(k) ,Z(j)=Π_(n=0) ^(j−1)Y(j) for j>1, and Z(1)=1 for j=1. DCI_length is thelength of DCI, and b_(k) is a binary representation of received DCI.That is, from Equation 1, an option (Field(j)th option) corresponding toField(j) in the j-th DCI may be selected.

For example, Table 3 below shows a case in which DCI includes threefields, and each field includes three options. If bits required for eachfield in the DCI are 2 bits, since there are a total of 3 fields, atotal of 6 bits are required for these fields. However, according to thepresent embodiment, all options of three fields may be expressed withonly 5 bits. In Table 3, code points 11011 to 11111 may be reserved.

TABLE 3 First field Second field Third field Y(1) = 3, Y(2) = 3, Y(3) =3, Z(1) = 1, Z(2) = 3, Z(3) = 9, floor(X/Z(1)) floor(X/Z(2))floor(X/Z(3)) mod Y(1) = mod Y(2) = mod Y(3) = X X floor(X/1) floor(X/3)floor(X/9) (binary) (decimal) mod 3 mod 3 mod 3 00000 0 0 0 0 00001 1 10 0 00010 2 2 0 0 00011 3 0 1 0 00100 4 1 1 0 00101 5 2 1 0 00110 6 0 20 00111 7 1 2 0 01000 8 2 2 0 01001 9 0 0 1 01010 10 1 0 1 01011 11 2 01 01100 12 0 1 1 01101 13 1 1 1 01110 14 2 1 1 01111 15 0 2 1 10000 16 12 1 10001 17 2 2 1 10010 18 0 0 2 10011 19 1 0 2 10100 20 2 0 2 10101 210 1 2 10110 22 1 1 2 10111 23 2 1 2 11000 24 0 2 2 11001 25 1 2 2 1101026 2 2 2 11011 27 — — — 11100 28 — — — 11101 29 — — — 11110 30 — — —11111 31 — — —

Referring to Table 3, for example, when 01100 (binary) is indicated byDCI to the UE, Field(1)=0, Field(2)=1, and Field(3)=1 may be obtained.That is, it may be seen that Field(1) which is a first field of DCI isindicated as the zeroth option, Field(2) which is a second field of DCIis indicated as the first option, and Field(3) which is a third field ofDCI is indicated as the first option.

Hereinafter, a method of determining the length of a DCI format isdisclosed. In a Release 15 NR system of 3GPP, for example, DCI formatsof different lengths may be defined as follows.

1) Fallback DCI (DCI formats 0_0 and 1_0) in a common search space

2) Fallback DCI (DCI formats 0_0 and 1_0) in a UE-specific search space

3) Non-fallback DCI (DCI format 0_1) for scheduling of PUSCH

4) Non-fallback DCI (DCI format 1_1) for scheduling of PDSCH

However, the UE may decode DCI formats having up to three differentlengths, but may not concurrently decode four DCI formats havingdifferent lengths. Therefore, when the lengths of all of four DCIsaccording to 1) to 4) are different from each other, it is required tomatch to the lengths of other DCI formats by increasing or decreasingthe lengths of some DCI formats. For example, if the lengths of all offour DCI formats are different, the base station may match the fallbackDCI in the UE-specific search space to have the same length as thelength of the fallback DCI in the common search space.

More specifically, the fallback DCI in the UE-specific search space andthe fallback DCI in the common search space may have different lengthsof a frequency domain resource assignment (FDRA) field. The length ofthe FDRA field of the fallback DCI in the common search space isdetermined according to the size of CORESET# 0 configured in a cellinitial access operation and the size of an initial DL BWP configuredvia system information (SIB1). However, the length of the FDRA field ofthe fallback DCI in the UE-specific search space is determined accordingto an active DL BWP. According to the present embodiment, in order tomatch the fallback DCI in the UE-specific search space with the lengthof the fallback DCI in the common search space, the base station maytruncate a most significant bit (MSB) of the FDRA field of the fallbackDCI in the UE-specific search space.

For reference, the base station may configure the length of thenon-fallback DCI (DCI format 0_1) for scheduling of a PUSCH and thenon-fallback DCI (DCI format 1_1) for scheduling of the PDSCH for the UEvia RRC signaling. Here, the length of the non-fallback DCI forscheduling of the PUSCH and the non-fallback DCI for scheduling of thePDSCH may be configured to be the same. If the length of thenon-fallback DCI (DCI format 0_1) for scheduling of the PUSCH and thenon-fallback DCI (DCI format 1_1) for scheduling of the PDSCH are thesame, the DCI formats include a 1-bit indicator. That is, in thenon-fallback DCI for scheduling of the PUSCH, the 1-bit indicator has avalue of 0, and in the non-fallback DCI for scheduling of the PDSCH, the1-bit indicator has a value 1. More specifically, a method ofdetermining DCI formats of up to three different lengths in Release 15is as follows.

A first operation includes determining the length of the fallback DCI(DCI formats 0_0 and 1_0) in the common search space by the UE or thebase station. Specifically, the UE or the base station determines thelength of DCI format 0_0 on the basis of an initial UL BWP, anddetermines the length of DCI format 1_0 on the basis of the size ofCORESET # 0 (if no initial DL BWP has been configured) or determines thelength of DCI format 1_0 on the basis of the initial DL BWP (if theinitial DL BWP has been configured). If the lengths of DCI format 0_0and DCI format 1_0 are different, the UE or the base station truncatesor performs zero-padding of MSBs of an FDRA field of DCI format 0_0 soas to match the length of DCI format 0_0 to the length of DCI format1_0.

A second operation includes determining the length of the fallback DCI(DCI formats 0_0 and 1_0) in the common search space by the UE or thebase station. Specifically, the UE or the base station determines thelength of DCI format 0_0 on the basis of an activated UL BWP, anddetermines the length of DCI format 1_0 on the basis of an activated DLBWP. If the lengths of DCI format 0_0 and DCI format 1_0 are different,the UE or the base station truncates or performs zero-padding of theMSBs of the FDRA field of DCI format 0_0 so as to match the length ofDCI format 0_0 to the length of DCI format 1_0.

A third operation includes determining the lengths of the non-fallbackDCI (DCI format 0_1) for scheduling of the PUSCH and the non-fallbackDCI (DCI format 1_1) for scheduling of the PDSCH. If the length of DCIformat 0_1 is the same as the length of the fallback DCI (DCI formats0_0 and 1_0) in the UE-specific search space, the UE or the base stationinserts “0” of a 1-bit length into the non-fallback DCI (DCI format 0_1)for scheduling of the PUSCH. If the length of DCI format 1_1 is the sameas the length of the fallback DCI (DCI formats 0_0 and 1_0) in theUE-specific search space, the UE or the base station inserts “0” of a1-bit length into the non-fallback DCI (DCI format 0_1) for schedulingof the PDSCH.

A fourth operation includes checking the lengths of the DCI formatsadjusted by the UE or the base station according to the first to thirdoperations. If there are three or fewer different lengths among all DCI,the UE is able to perform decoding, and therefore the lengths are nolonger matched. Conversely, if the number of different lengths exceedsthree, the lengths are additionally adjusted via a fifth operation.

The fifth operation includes adjusting the lengths of DCI formats tothree by the UE or the base station. To this end, the UE or the basestation may exclude 1 bit added in the third operation. The UE or thebase station changes the length of the FDRA field of the fallback DCI(DCI formats 0_0 and 1_0) in the UE-specific search space. Specifically,the UE or the base station may determine the length of DCI format 1_0 onthe basis of the size of CORESET # 0 (if no initial DL BWP has beenconfigured), and may determine the length of DCI format 1_0 on the basisof the initial DL BWP (if the initial DL BWP has been configured). TheUE or the base station determines the length of DCI format 0_0 on thebasis of the initial UL BWP. If the lengths of DCI format 0_0 and DCIformat 1_0 are different, the UE or the base station truncates orperforms zero-padding of the MSBs of the FDRA field of DCI format 0_0 soas to match the length of DCI format 0_0 to the length of DCI format1_0.

The first to fifth operations as described above may be performed by theprocessor 110 or the processor 210 of FIG. 11.

According to another embodiment of the present specification, the UE orthe base station may configure a DCI format of a new length in order tosupport a new URLLC service. This is referred to as compact DCI forconvenience. The length of each field of compact DCI may be configuredvia RRC signaling. Therefore, according to the configuration via RRCsignaling, the length of the compact DCI may be configured to be lessthan the length of Release 15 fallback DCI by 16 bits, may be configuredto be the same as the length of the Release 15 fallback DCI, and may beconfigured to be longer than the length of the Release 15 fallback DCI.According to the present embodiment, DCI formats of two new lengths maybe defined as follows.

5) Compact DCI for scheduling of PUSCH

6) Compact DCI for scheduling of PDSCH

In order to decode the DCI formats of 1), 2), 3), 4), 5), and 6) havingdifferent lengths, the UE needs to match the lengths of the DCI formats.

First, it is assumed that the UE supporting a URLLC service of Release16 may concurrently receive DCI formats having three different lengths.In such a situation, a method of adjusting or matching the lengths ofDCI according to the present embodiment is as follows.

As an example, the UE first matches the sizes of Release 15 DCI formats.That is, the UE determines DCI formats of up to three different lengthsover the first to fifth operations described above. Thereafter, the UEdetermines the length of compact DCI as follows.

If there are three DCI formats of Release 15, which have differentlengths, compact DCI for scheduling of the PUSCH and compact DCI forscheduling of the PDSCH may be configured to have one length among thepreviously determined lengths of the DCI formats of Release 15.

In one aspect, when configuring the compact DCI for the UE via RRCsignaling, the base station may directly inform about the length that acompact DCI format should have.

In another aspect, when configuring the compact DCI for the UE via RRCsignaling, the base station may inform about the length of the compactDCI by indicating another DCI format having the same length as that ofthe compact DCI. For example, RRC signaling is 2 bits, wherein, if avalue of RRC signaling is 00, the fallback DCI (DCI formats 0_0 and 1_0)in the common search space is indicated, if the value is 01, thefallback DCI (DCI formats 0_0 and 1_0) in the UE-specific search spaceis indicated, if the value is 10, the non-fallback DCI (DCI format 0_1)for scheduling of the PUSCH is indicated, and if the value is 11, thenon-fallback DCI (DCI format 1_1) for scheduling of the PDSCH isindicated. That is, the length of the compact DCI may have the samelength as that of other DCI formats indicated via the RRC signaling.

In another aspect, when configuring the compact DCI for the UE via RRCsignaling, the base station may indicate an index corresponding to thesame length as that of the compact DCI from among length indexes thatother DCI formats may have. For example, a lowest index value (forexample, “0” when length indexes of other DCI formats are given as 0, 1,and 2) of the RRC signaling corresponds to a DCI format of a shortestlength, and a highest index value (for example, “2” when length indexesof other DCI formats are given as 0, 1, and 2) corresponds to a DCIformat of a longest length.

In another aspect, the UE may not receive the length of the compact DCIvia separate RRC signaling. That is, the UE may determine the length ofthe entire compact DCI on the basis of the length of each field of thecompact DCI. Specifically, it is assumed that the lengths of the Release15 DCI formats are given as A, B, and C. Here, it is assumed that A<B<C,and X be a sum of the length of each field of the compact DCI. Then, thelength of the compact DCI is determined to be a shortest length amongRelease 15 DCI formats longer than X. If there is no Release 15 DCIformat longer than X, the length of the compact DCI is matched to thelength of a longest Release 15 DCI format. For example, if A<X<B, (B-X)bits are added to the compact DCI, thereby matching the length thereofto B bits. If C<X, (X-C) bits are excluded from the compact DCI, therebymatching the length thereof to C bits.

As described above, indicating or configuring the length of the compactDCI via RRC signaling may be performed by the communication module 220of FIG. 11.

A method of adjusting the length of the compact DCI by the UE is asfollows.

The UE determines the length of the compact DCI according to the RRCsignaling. If the sum of the lengths of all fields of the compact DCI issmaller than the length of the DCI format configured via the RRCsignaling, the UE may fill in insufficient bits. All values to be filledherein may be 0 or may be given as a CRC value. On the other hand, ifthe sum of the lengths of all fields of the compact DCI is greater thanthe length of the DCI format configured via the RRC signaling, the UEmay subtract excess bits.

In one aspect, the excess bits may be subtracted from one particularfield. For example, the excess bits may be subtracted from the FDRAfield.

In another aspect, the excess bits may be sequentially subtracted from apredetermined number of specific fields, and may be subtracted by 1 bitfrom an MSB of each field. For example, the excess bits are sequentiallysubtracted from the FDRA field and a TDRA field, and may be subtractedfrom the MSB of each field.

It may be configured not to reduce a specific field to a preconfiguredminimum length or less when the UE subtracts the excess bits from thespecific field. That is, the UE subtracts the excess bits from a firstfield, but, when the length of the first field is reduced to the minimumlength, the length of a subsequent second field is reduced.

The method of adjusting the length of the compact DCI by the UEaccording to the embodiment may be performed by the processor 110 ofFIG. 11.

According to the present embodiment, the length of a DCI format that maybe monitored by the UE is determined according to the length of theRelease 15 DCI format. Therefore, there is a disadvantage that thecompact DCI cannot be made shorter than the Release 15 DCI format.

As another embodiment to solve this problem, the UE first adjusts thesizes of Release 15 DCI formats. If the Release 15 DCI formats havethree lengths, and the length of the compact DCI is different from thelengths of the Release 15 DCI formats, the UE may adjust the length ofthe DCI format according to the following procedure. First, the UEmatches the lengths of the non-fallback DCI (DCI format 0_1) forscheduling of the PUSCH and the non-fallback DCI (DCI format 1_1) forscheduling of the PDSCH to be the same. Here, a DCI format having ashort length is padded with 0 so as to be matched to a DCI format havinga long length. In this way, by matching the length of the non-fallbackDCI and not matching the length of the compact DCI, the compact DCIhaving a short length may be configured and used.

When it is assumed that the fifth operation is not performed, anembodiment that can be modified is as follows. The UE first adjusts thesizes of Release 15 DCI formats. If the length of the compact DCIconfigured for the UE is different from the DCI lengths of the Release15 DCI formats, and the total lengths exceed three lengths, the UEperforms the fifth operation. That is, the UE matches the length of thefallback DCI (DCI formats 0_0 and 1_0) in the UE-specific search spaceto the length of the fallback DCI (DCI formats 0_0 and 1_0) in thecommon search space. Thereafter, if the lengths of the DCI formats stillexceed three lengths, the UE may again perform the method of determiningthe DCI length according to the aforementioned first to fifthoperations.

As another example of the present disclosure, the UE may receive DCIformats with different lengths in each slot. A specific embodiment forthis includes checking the lengths of up to three DCI formats for eachslot by the UE. The UE may not monitor a DCI format in a specific slotaccording to a period of the search space. In this case, the UE maydetermine whether there are more than up to three types of lengths, byusing only the lengths of DCI formats that are monitored, except for aDCI format that is not monitored. If there are more than up to threetypes of lengths in the slot, the UE may adjust the length of the DCIformat according to the aforementioned embodiment. In other slots, sincethe number of the lengths of the DCI format is three or fewer, thelength of the DCI format may not be separately adjusted.

The method and system of the present disclosure are described inrelation to specific embodiments, but configuration elements, a part ofor the entirety of operations of the present disclosure may beimplemented using a computer system having general purpose hardwarearchitecture.

The foregoing descriptions of the present disclosure are forillustration purposes, and those skilled in the art, to which thepresent disclosure belongs, will be able to understand that modificationto other specific forms can be easily achieved without changing thetechnical spirit or essential features of the present disclosure.Therefore, it should be understood that the embodiments described aboveare illustrative and are not restrictive in all respects. For example,each element described as a single type may be implemented in adistributed manner, and similarly, elements described as beingdistributed may also be implemented in a combined form.

The scope of the present disclosure is indicated by claims to bedescribed hereinafter rather than the detailed description, and allchanges or modifications derived from the meaning and scope of theclaims and their equivalent concepts should be interpreted as beingincluded in the scope of the present disclosure.

1-20. (canceled)
 21. A user equipment (UE) for use in a wirelesscommunication system, the UE comprising: a communication module; and aprocessor configured to control the communication module, wherein theprocessor is configured to: receive two or more downlink controlinformation (DCI) for downlink scheduling, wherein each DCI includes: atime-domain resource allocation for a corresponding physical downlinkshared channel (PDSCH), and an indicator related to hybrid automaticrepeat and request acknowledgement (HARQ-ACK) multiplexing, theindicator having one of two values; receive two or more PDSCHscorresponding to the two or more DCIs, each PDSCH being associated witha respective one of the two values of the indicator; as for the two ormore PDSCHs, generate a first HARQ-ACK codebook associated with a firstvalue of the indicator, and generate a second HARQ-ACK codebookassociated with a second value of the indicator; and based on a firstphysical uplink control channel (PUCCH) resource for the first HARQ-ACKcodebook being overlapped with a second PUCCH resource for the secondHARQ-ACK codebook, perform only one PUCCH transmission by using one ofthe first and second PUCCH resources, associated with a pre-determinedone of the two values of the indicator.
 22. The UE of claim 21, wherein,based on the first PUCCH resource for the first HARQ-ACK codebook notbeing overlapped with the second PUCCH resource for the second HARQ-ACKcodebook within a slot, two PUCCH transmissions are performed by usingthe first and second PUCCH resources in the slot.
 23. The UE of claim22, wherein the first HARQ-ACK codebook is a semi-static HARQ-ACKcodebook, and the second HARQ-ACK codebook is a dynamic HARQ-ACKcodebook.
 24. The UE of claim 21, wherein each DCI further includes aninterval between a reception timing of the corresponding PDSCH and atransmission timing of a corresponding PUCCH, and the interval isdefined in units of a sub-slot.
 25. The UE of claim 21, wherein the onlyone PUCCH transmission carries either the first HARQ-ACK codebook or thesecond HARQ-ACK codebook, associated with the pre-determined one of thetwo values of the indicator.
 26. A method for use by a user equipment(UE) in a wireless communication system, the method comprising:receiving two or more downlink control information (DCI) for downlinkscheduling, wherein each DCI includes: a time-domain resource allocationfor a corresponding physical downlink shared channel (PDSCH), and anindicator related to hybrid automatic repeat and request acknowledgement(HARQ-ACK) multiplexing, the indicator having one of two values;receiving two or more PDSCHs corresponding to the two or more DCIs, eachPDSCH being associated with a respective one of the two values of theindicator; as for the two or more PDSCHs, generating a first HARQ-ACKcodebook associated with a first value of the indicator, and generatinga second HARQ-ACK codebook associated with a second value of theindicator; and based on a first physical uplink control channel (PUCCH)resource for the first HARQ-ACK codebook being overlapped with a secondPUCCH resource for the second HARQ-ACK codebook, performing only onePUCCH transmission by using one of the first and second PUCCH resources,associated with a pre-determined one of the two values of the indicator.27. The method of claim 26, wherein, based on the first PUCCH resourcefor the first HARQ-ACK codebook not being overlapped with the secondPUCCH resource for the second HARQ-ACK codebook within a slot, two PUCCHtransmissions are performed by using the first and second PUCCHresources in the slot.
 28. The method of claim 27, wherein the firstHARQ-ACK codebook is a semi-static HARQ-ACK codebook, and the secondHARQ-ACK codebook is a dynamic HARQ-ACK codebook.
 29. The method ofclaim 26, wherein each DCI further includes an interval between areception timing of the corresponding PDSCH and a transmission timing ofa corresponding PUCCH, and the interval is defined in units of asub-slot.
 30. The method of claim 26, wherein the only one PUCCHtransmission carries either the first HARQ-ACK codebook or the secondHARQ-ACK codebook, associated with the pre-determined one of the twovalues of the indicator.
 31. A base station (BS) for use in a wirelesscommunication system, the BS comprising: a communication module; and aprocessor configured to control the communication module, wherein theprocessor is configured to: transmit two or more downlink controlinformation (DCI) for downlink scheduling, wherein each DCI includes: atime-domain resource allocation for a corresponding physical downlinkshared channel (PDSCH), and an indicator related to hybrid automaticrepeat and request acknowledgement (HARQ-ACK) multiplexing, theindicator having one of two values; transmit two or more PDSCHscorresponding to the two or more DCIs, each PDSCH being associated witha respective one of the two values of the indicator; and based on afirst physical uplink control channel (PUCCH) resource for a firstHARQ-ACK codebook being overlapped with a second PUCCH resource for asecond HARQ-ACK codebook, receive only one PUCCH transmission by usingone of the first and second PUCCH resources, associated with apre-determined one of the two values of the indicator, wherein, as forthe two or more PDSCHs, the first HARQ-ACK codebook is provided inassociation with a first value of the indicator, and the second HARQ-ACKcodebook is provided in association with a second value of theindicator.
 32. The BS of claim 31, wherein, based on the first PUCCHresource for the first HARQ-ACK codebook not being overlapped with thesecond PUCCH resource for the second HARQ-ACK codebook within a slot,two PUCCH transmissions are received by using the first and second PUCCHresources in the slot.
 33. The BS of claim 32, wherein the firstHARQ-ACK codebook is a semi-static HARQ-ACK codebook, and the secondHARQ-ACK codebook is a dynamic HARQ-ACK codebook.
 34. The BS of claim31, wherein each DCI further includes an interval between a transmissiontiming of the corresponding PDSCH and a reception timing of thecorresponding PUCCH, and the interval is defined in units of a sub-slot.35. The BS of claim 31, wherein the only one PUCCH transmission carrieseither the first HARQ-ACK codebook or the second HARQ-ACK codebook,associated with the pre-determined one of the two values of theindicator.
 36. A method for use by a base station (BS) in a wirelesscommunication system, the method comprising: transmitting two or moredownlink control information (DCI) for downlink scheduling, wherein eachDCI includes: a time-domain resource allocation for a correspondingphysical downlink shared channel (PDSCH), and an indicator related tohybrid automatic repeat and request acknowledgement (HARQ-ACK)multiplexing, the indicator having one of two values; transmitting twoor more PDSCHs corresponding to the two or more DCIs, each PDSCH beingassociated with a respective one of the two values of the indicator; andbased on a first physical uplink control channel (PUCCH) resource for afirst HARQ-ACK codebook being overlapped with a second PUCCH resourcefor a second HARQ-ACK codebook, receiving only one PUCCH transmission byusing one of the first and second PUCCH resources, associated with apre-determined one of the two values of the indicator, wherein, as forthe two or more PDSCHs, the first HARQ-ACK codebook is provided inassociation with a first value of the indicator, and the second HARQ-ACKcodebook is provided in association with a second value of theindicator.
 37. The method of claim 36, wherein, based on the first PUCCHresource for the first HARQ-ACK codebook not being overlapped with thesecond PUCCH resource for the second HARQ-ACK codebook within a slot,two PUCCH transmissions are received by using the first and secondPUCCHs are received in the slot.
 38. The method of claim 37, wherein thefirst HARQ-ACK codebook is a semi-static HARQ-ACK codebook, and thesecond HARQ-ACK codebook is a dynamic HARQ-ACK codebook.
 39. The methodof claim 36, wherein each DCI further includes an interval between atransmission timing of the corresponding PDSCH and a reception timing ofthe corresponding PUCCH, and the interval is defined in units of asub-slot.
 40. The method of claim 36, wherein the only one PUCCHtransmission carries either the first HARQ-ACK codebook or the secondHARQ-ACK codebook, associated with the pre-determined one of the twovalues of the indicator.